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Dexamethasone (8 mg/day im) has been administered to rhesus monkeys (Macaca mulatto) from days 146–156 of pregnancy, until term. This treatment was ineffective in precipitating premature delivery, and the monkeys delivered spontaneously at the expected time (day 166–176). Maternal peripheral plasma progesterone concentrations were unaffected by the dexamethasone treatment. However, administration of the synthetic glucocorticoid resulted in a marked suppression of the maternal plasma estrone and estradiol-17β concentrations in all animals. In the 4 monkeys in which injections of dexamethasone were initiated earliest (days 146–150), the plasma unconjugated estrogen levels at term were 15–40% of those found prior to the start of treatment. At autopsy, the adrenal glands from the fetuses of dexamethasone-treated monkeys had markedly atrophied, and showed appreciable regression of the fetal zone. It is suggested that dexamethasone crosses the placenta and inhibits fetal ACTH release, resulting in regression of...

Plasma estradiol-17beta and total progestins were determined to delineate the relationship between preovulatory estradiol-17beta peak and ovulation in the bonnel monkey (Macaca radiata). 6 monkeys were studied for 15 menstrual cycles. In subsequent cycles serial laparotomy was performed in 5 of the 6 monkeys to correlate ovarian morphology to plasma estradiol-17beta. In 11 of the 15 cycles estradiol-17beta peaks were 3- to 7-fold above baseline levels near the time of expected ovulation (Cycle Days 7-12). Plasma progestin rose significantly from follicular phase levels of .5 ng/ml to 2.6 ng/ml the day of the estradiol-17beta peak with peak levels of 4.5 ng/ml on the following day. Ovarian morphology in 4 of the 5 observed by laparotomy demonstrated ovulation within 48 hours following an estradiol-17beta peak of approximately 300 pb/ml.

Twin baboon embryos were acquired by hysterotomy from a multipara on the twenty-sixth day of gestation. All preceding and succeeding pregnancies yielded single births. This case of dichorionic, diamniotic twins is unique because there is a seven day difference in the morphological development of the two embryos. The embryos are approximately the same fertilization age because mating was limited to one 12 hour period of the menstrual cycle. In addition only one corpus luteum was identified at laparotomy. Both twins were males as indicated by the sex chromatin, eliminating the positive identification of dizygosity. Several alternatives for the twins' origin are cited. One possibility is that there was a division of the blastomeres at the two-cell stage, or at some other stage before implantation, yielding monozygotic twins. Another possibility is that both ova arose from the same follicle, yielding dizygotic twins. The larger embryo is 2.0 mm in greatest length and has six pairs of somites, and is similar to ten other baboon embryos 25–26 days old. The smaller embryo is of the trilaminar disc stage and is comparable in developmental features to five other baboon embryos 18–19 days old. The morphological features of each placenta are comparable in development to the age of its respective embryo.

Molar tooth buds of known aged baboon fetuses were removed and stained in alizarin red S. The sequences of cusp calcification and coalescences were studied in the deciduous molars. The cusp calcification sequence was similar in the baboon, rhesus monkey, and man; the coalescence pattern of the baboon and rhesus monkey differed from that of man.

The arrangement of the facial nerve was studied in 21 baboon embroys and fetuses, 2.6–36.0 mm crown-rump length, (25–54 days fertilization age) and one adult. The head and neck regions of eight specimens were reconstructed graphically or with wax. The extramedullary part of the right nerve was traced microscopically and its configuration mapped. In early embryos (11–36 somites, 2.6–6.0 mm) the facial part of the facioacoustic primordium is either in close proximity or contacts the second arch epibrachial placode. It becomes a separate nerve (6.9–16.5 mm embryos) as the geniculate ganglion forms and the placode disappears. The first branches are the chorda tympani and greater petrosal. The pars intermedia and chorda tympani are large at 9 mm and the parent nerve terminates distally as a loose network of intermingling fibers. In 14.8–16.3 mm embryos connections are established with the deep petrosal and maxillary, and the tympanic, vagus and lingual nerves. Peripheral branches course into the occipital, cervical and mandibular regions. Between 18.3 and 36.0 mm the temporofacial and cervicofacial rami become evident and peripheral branches also extend into temporal, zygomatic and buccal regions. Communications are formed with branches of the auriculotemporal, zygomatic, infraorbital, buccal, mental, transverse cervical and great auricular nerves. Branches to the temporal and zygomatic areas lag in development.

The arrangement of the trigeminal nerve or its primordium was studied in 27 baboon embryos and fetuses 2.5–63.0 mm (crown-rump length), 24–64 days insemination age. The head region of seven representative specimens was reconstructed graphically or with wax. The entire extramedullary part of the nerve, including the related parasympathetic ganglia, was traced microscopically in serial sections stained with either hematoxylin and eosin or protargol-S and eosin. The crest is first apparent in five somite embryos (24 days) and becomes more prominent and extends farther ventrally by eight somites (25 days). Lateral and ventral to the crest the ectoderm shows a slight, gradual thickening but not as a distinct placode. At 11–19 somites (25–27 days) the primordium is a column of cells that becomes loosely arranged as it terminates in the first arch. By 21–22 somites (28 days) the enlarged primordium has the three divisions with the mandibular being most prominent and closely applied to ectoderm near the first groove. Between 26 and 36 somites (29–30 days) the trigemial ganglion and motor root become apparent. The distal part of each division is eosinophilic and fibrous. Branches from each division begin to form as sprays of fibers by 6.9–9.0 mm (32–33 days) and the primordia of the four related parasympathetic ganglia become evident. Many of the definitive branches and their communications with other nerves are present at 11.6–16.5 mm (36–40 days). Most of the branches and many communications with the facial nerve are established by 18.3–36.0 mm (45–54 days). All of the named branches, including the meningeal branches, are present at 63 mm (64 days).

The pioneer study of Carpenter (1942) characterized oestrous behaviour in rhesus monkeys by criteria related to increased sexual behaviour and by `increased aggressiveness . . and wounds'. Subsequent studies of rhesus monkeys by Bernstein (1963) and Lindburg (1971) have confirmed a mid-cycle increase in behavioural arousal which appears to coincide with ovulation (as judged from subsequent pregnancy data). Loy (1970) now reports an increase in so\x=req-\ called `estrous behavior' both perimenstrually and at mid-cycle in free\x=req-\ ranging rhesus monkeys. Rowell (1963) has observed increased perimenstrual aggressive interaction, but differentiates increased aggression received during the premenstrual week from increased aggression exerted on cage mates during the week after the onset of menstruation. The present study is an attempt to relate bite wounds and menstrual cycle data for groups of rhesus, Macaca mulatta, females maintained in groups caged in the breeding colony of the California Primate Research Center. This is a retrospective analysis of routine laboratory records over the 16-month period from July 1967 to November 1968, representing 2638 'female months', i.e. 6 months' records for thirty-six cages with an average monthly total population of 208+15 (S.D.) plus an additional 10 months' records for eighteen of these cages with an average monthly total population of 123+10. Each female was inspected daily for signs of menstruation (blood in vulva), fresh bite wounds, and illness. At the time of observation, only menstruation data were utilized for breeding purposes. In the course of these records, a total of 130 bite wounds was recorded, apparently resulting from the most severe aggressive encounters occurring under the conditions of relatively high crowding stress in the caged group. Bite wounds represent a rather constant proportion of total agonistic interaction in a social group (T.E. Rowell, unpublished observations) and thus can serve as a crude indicator of behavioural changes. The wounds recorded here appeared to

The concentration of prostaglandin F (PGF) has been measured in the peripheral plasma of normal rhesus monkeys (Macaca mulatta) during the final third of gestation, and in monkeys treated with dexamethasone or PGF2α after day 145 of pregnancy. Daily administration of PGF2α (10–15 mg/day im) reliably induced abortion within 3–6 days. However, dexamethasone (8 mg/day im from day 145) had no effect on the length of gestation. The concentration of PGF in the femoral venous plasma of untreated or dexamethasone-treated monkeys was highly variable, both in serial samples taken from the same animal and in samples taken from different animals at the same time of gestation. There was no indication of an effect of dexamethasone treatment on the plasma PGF levels, nor did the concentration of PGF increase during late pregnancy before spontaneous parturition. These results show that the myometrium of the pregnant rhesus monkey is highly sensitive to exogenous PGF2α during late gestation. However, a significant increase in the peripheral plasma concentration of PGF prior to the onset of labor was not observed.

One hundred and twenty-one ejaculates obtained by penile electrical stimulation of five highly fertile rhesus males are described in appearance, interaction of coagulum and liquid components, and liquid to coagulum ratios. Three types of gross coaguluni appearance are identified. The coagulum comprises 55-68% of the ejaculate by volume displacement measurement. A low volume of semen is never trapped in the coagulum and has a much higher sperm density than liquid released by contraction of the coagulum within 15 mm after ejaculation. No evidence of coagulum liquefaction was found and both liquid volume and liquid portion sperm count were reduced by incorporation into the coagulum if contact was continued. Enzymatic digestion of the coagulum unsatisfactorily causes sperm destruction and loss of motility, limiting its usefulness. Early separation of the coagulum and liquid portions of the ejaculate is recommended for semen assessment studies, and other contemplated utilization of electroejaculates. Surgical removal of the coagulating gland would be ideal if long-term use of electroejaculated semen is contemplated for certain animals. Despite the reports of good success in obtaining nonhuman primate ejaculates by electroejaculation, there are few data on the characteristics of the ejaculates. Mastroianni et a!. (1963) described the ejaculate in the rhesus monkey as initially liquid, with coagulation occurring within seconds of ejaculation, followed by liquefaction of 30% of the total volume within 30 mm. His observations were that liquefaction continued very slowly after 30 mm and was never complete. Weisbroth et at. (1965) stated that enzymatically digested coagulum contained about half the total sperm and that the number of sperm present in liquid semen was dependent upon the amount of coagulum which was autolyzed. Hoskins et a!. (1967) reported that 30-70% of the total spermatozoa were found in the coagulum after 30 mm of incubation. For none of these reports are data available dealing with times involved from ejaculation to examination and sperm counting, or the length of time for which coagulum was allowed to remain in contact with the liquid portion of the semen after initial examination. Van Pelt et at. (1970) described most carefully detailed observations on the physical characteristics of the rhesus monkey ejaculate. He stated that the initial portion was a tan liquid of extremely high sperm count followed by a clear, more viscuous liquid which coagulated entrapping the initial liquid portion. He then described “liquefaction” as actually an exudation of sperm-containing liquid, caused by contraction of the coagulum, which was virtually complete within 30 mm.

A procedure has been developed whereby cell proliferation during early embryogenesis of the monkey can be studied radioautographically following in vivo exposure to relatively small amounts of 3H-thymidine.

The concentrations of progesterone, estrone and estradiol-17β have been measured by radioimmunoassay in serial samples of peripheral plasma from rhesus monkeys (Macaca mulatto) during the final third of normal pregnancy, and during the induction of abortion with prostaglandin F2α (PGF2α). In 3 out of 5 animals, the plasma progesterone concentration increased during the 5–10 days preceding spontaneous labor. In no animal did the progesterone concentration decrease before parturition. The concentration of estradiol-17β was greater than that of estrone in most plasma samples. The levels of both estrogens in maternal plasma increased within 5 days before parturition, but decreased rapidly after the fetus had been delivered. Daily maternal injections of PGF2α (10–15 mg/day) administered around day 150 of pregnancy reliably induced premature delivery. The concomitant steroid hormone changes were variable, although most monkeys showed a decline in the plasma progesterone and estrogen levels during the final 24 h...

Progesterone (P) levels in the peripheral blood of parous bonnet monkeys (Macaca radiata) were studied by a competitive protein-binding radioassay method during the menstrual cycle and in pregnancy. During the menstrual cycle P levels averaged less than .5 ng/ml during the first 9 days and then began to rise considerably between Days 9-11 reaching maximal levels on Day 18. P levels then showed a considerable decline by Day 24 of the cycle when compared with levels during Days 15-23. 2-3 days prior to menstruation P levels were less than 1 ng/ml. P levels during the first 12 days postbreeding were higher than during the luteal phase but presented a similar pattern. A definite divergence of P levels in pregnancy compared with nonpregnant animals occurred at Day 15 of pregnancy or Day 24 of the menstrual cycle when levels in pregnant animals were maintained and levels in nonpregnant animals significantly declined. This devergence suggests that there is a well-defined period in which the corpus luteum regresses if the animal is not pregnant. P concentrations began to decline on Day 35 postbreeding and continued until Days 45-50. Until Days 145-150 P levels varied and thereafter began to increase. The greatest increase in P levels was observed during the last 6 days before delivery. P levels which averaged 20 ng/ml about 12 hours before delivery declined to 2 ng/ml at 12 hours postpartum.

A controlled breeding program was used to collect baboon embryos of known insemination ages. Serial sections of the palatine region of 37 embryos and fetuses from 30 to 64 days (d) (estimated fertilization age) werestudied microscopically and by graphic or wax reconstruction. One 100-day fetuswas partially dissected. Nasal placodes appeared in Stage XIV (30 d, 4.3–6.0 mm).By Stage XVI (33–36 d, 6.9–9.0 mm) nasal pits developed. The primary palate and palatine processes were present at Stage XVII (36 d, 11.3–11.6 mm). Subsequent development produced rostrodorsal and vertical lengthening of the palatine processes. Rostrally they slanted caudomedially toward the base of the tongue, and dorsally they remained vertically oriented lateral to the tongue in Stage XXI (43–45 d, 18.3–19.6 mm). In Stage XXII (47 d, 22–24 mm) the midpalatine processesbegan to rotate to a horizontal position. By Stage XXIII (45–50 d, 25.8–28.0 mm)the rostral two-thirds of the palatine processes were horizontally oriented cranialto the tongue. They were fusing to each other and to the nasal septum. The dorsalone-third of the palatine processes were assuming a horizontal position by medialprojection. In the 53-d fetuses (39.6–48.0 mm) the hard and soft palates wereformed except for the uvula, which remained divided until sometime after 64 d(63.0 mm). Epithelial remnants were not formed in the soft palate, suggestingthat this area was formed by mesenchymal merging without epithelial fusion.

Since the well-known work by Hamburger and Hamilton ( 195 1) on normal chick enlbyros appeared, a number of workers have “? staged― embryos of various species of birds. They clearly established morphological and structural characteris tics as more reliable criteria than chronological age in the staging of chick enibryos. Rempel and Eastlick ( 1957) showed constant differences between embryos of the White Silkie bantam and standard varieties of the domestic chicken. Koeke ( 1958) described the embryonic stages of the domestic duck. Mumi and Kosin ( 1960) correlated the development of broad-breasted bronze turkey eiiibryos with the chick. Although few significant differences were recorded, they showed that the turkey embryo has a distinctive structure, the “? snood― or “? leader,― which serves as an important criterion for older stages. Hanson ( 1954) applied candling and special photographic techniques in determining the age of mallard. wood duck afl(l bob-white quail embryos. His primary purpose was to determine the age of embryos at the nest site. In the present paper, normal stages of chick enhl)ryo development ( Hamburger and Hamilton, 1951 ) were used as the basis for establishing the stages of develop ment for the quail. It is known that the quail embryo takes approximately 23 days to hatch, as compared with 21 days in the chick. Thus, the niajor objective of this study was to correlate the developmental stages of quail and chick embryos, and to identify the periods of incubation when the quail embryo “? lags― behind in development. Since all photographs, descriptions and measurements are based on material fixed in FAA (5 ml. formalin, 90 ml. 70% ethyl alcohol, 5 ml. glacial acetic acid), minor distortions may have occurred. Freshly laid fertile eggs were obtained froni the State Ganie Farm, Mount Vernon, Illinois. They were incubated in a Farm Master incubator at a temperature of 99.5 F. dry bulb and about 89.0° F. wet bulb. During the course of this study several hundred embryos were examined from the unincubated stage until hatching. No constant differences were observed between ciuail and chick embryos through stage6 (25 hours) (Hamburger and Hamilton, 1951) and referenceto thesestages will be omitted. Between stages 7 and 14, which are based primarily on the number of pairs of visible somites, the quail embryo lags in development so that l)ystage 14 (22 somites) itis 12—16 hours olderthan the chick. The gradual lag in developmental ratecontinuesso thatb@ stage24 the quailembryo is24 hours behind the chick enibryo iii morphological development. Flexion and rotation of

The four pharyngeal pouches, pharyngeal grooves, and closing membranes of the dog form in an antero-posterior sequence but the encroachment of head mesoderm which results in obliteration of the closing membranes occurs in a posteroanterior sequence. No pharyngeal clefts are formed. The anlage of the auditory tube arises as a dorso-lateral extension from the dorsal surface of the first pharyngeal pouch and expands into an elongated tube directed toward the developing ear. The second pharyngeal pouch develops into a distinct tonsillar sinus dorso-lateral to the base of the tongue. The palatine tonsil extends into the tonsillar sinus, and both become covered by a fold of epithelium. The third pharyngeal pouch extends medially toward the developing thyroid after contacting the cervical sinus. The distal tip of the third pouch differentiates into Complex III which transforms into parathyroid III and thymus III. The distal tip of the fourth pharyngeal pouch, Complex IV, also extends in a medial direction after contacting the cervical sinus. Complex IV transforms into parathyroid IV and the ultimobranchial body.

Plasma progesterone levels were determined in the crab—eating macaque (Macaca fascicularis) during the menstrual cycle and pregnancy, including parturition. Menstrual cycles averaged 31 days in duration. Progesterone levels rose above 1 ng/ml plasma about 15 days prior to the onset of menstruation with peak values (7.8 ng/ml) observed on day 7 prior to menstruation. Progesterone levels declined to > 1 ng/ml 1–4 days before menstruation. Two animals studied daily for the first 30 days postbreeding, and then 2 times weekly, had 2 distinct progesterone peaks, one about IS days postbreeding and another at about 34 days with a low point in progesterone levels observed between these peaks at about days 23 to 25. The progesterone decline which followed the second peak reached minimal levels (1 to 2 ng/ml) by about day 45 of gestation. Progesterone levels increased gradually throughout the rest of gestation with average values of about 4 ng/ml observed the last 2 weeks prior to parturition. No significant changes...

Twenty-nine pregnancies were obtained in 21 female bonnet monkeys. The females were housed individually and were mated for a 2-h period, usually 2 days before midcycle. The day of mating was designated as day o of pregnancy. After pregnancy was confirmed by rectal palpation the animals each received 5, 10, or 30 mg/kg thalidomide orally, either as single doses on days 24, 25, 26, 27, 28, or 29 or once per day on days 25–27 or 41–44. With 5 and 10 mg/kg only malformations of the forelimbs were observed, characterized by total absence (amelia) or partial absence (meromelia) of the free limb. In all cases the malformations were more severe on the left side than the right. No craniocaudal developmental gradient was noted with 10 mg/kg. With 30 mg/kg forelimb and hindlimb malformations occurred, although the hindlimb malformations were mild and consisted essentially of either bowing or partial absence of the femur. A craniocaudal developmental gradient was evident with 30 mg/kg. Treatment during the time of palate closure (days 41–44) did not affect normal palate development. Absence and/or malformations of the uterus, ovaries, kidney, heart, brain, spleen, and umbilical arteries also occurred.

Vesiclulation and other anomalies were observed in the zona pellucida about the ovum of female baboons (Papio anubis) that had received treatment with Pergonal and human chorionic gonadotropin; and in somiie instances the zona pellucida was absent.