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Calbindin-D28k (CB), parvalbumin (PV) and calretinin (CR) are calcium-binding proteins (CaBPs) considered to be markers for certain subpopulations of neurons in the central nervous system. The aim of this study was to describe the pattern of distribution of CB-, PV- and CR-immunoreactive elements in the rabbit corticomedial amygdaloid complex during the postnatal period. The time course of changes in CaBPs expression during maturation of the selected nuclei indicates their diversity. During the first month after birth, CaBPs expression stabilizes earliest in the anterior cortical and then in the medial nuclei. Later, during the second month of postnatal life, the posteromedial and posterolateral cortical nuclei maturate. The central nucleus requires a considerably longer time to reach maturity - about three months are needed to stabilize CaBPs expression in all its subdivisions. This nucleus also shows the most differentiated, time-dependent distribution of CaBPs immunoreactivity (especially CB), distinct in its divisions. The differences in the CaBPs immunoreactivity confirm previous reports concerning dissimilar origin and development, and also reflect the diversity of connectivity of the amygdaloid body - the collection of nuclei, considered as one functional integrity.

Our intention in the present study was to ascertain whether NO-producing cells in the basolateral complex (BLC) and paracapsular intercalated nerve cell groups (Ip) of the amygdala are activated in the open field (OF) test. The material consisted of 8 adult rat brains. The OF test was applied throughout 10 min and 90 min before the death of the animals. The brain sections were double stained using the antibodies against c-Fos (marker of neuronal activation) and against nitric oxide synthase (NOS -- marker of NO-producing cells). The neurons containing NOS and those revealing c-Fos activity constituted distinct populations within both the BLC and Ip but NOS-immunoreactive fibres often surrounded the c-Fos-immunoreactive neurons. Our results suggest that (1) neurons of the basolateral complex of the amygdala and paracapsular intercalated islands are involved but probably not crucial for the open field stress response and (2) NOS-immunoreactive cells in the BLC and Ip are not activated after OF exposure.

The aim of the study was to estimate developmental changes in the rabbit basolateral complex (BLC) by stereological and histochemical methods. Material consisted of 45 brains of New Zealand rabbits (aged from 2 to 180 days, P2 to P180) of both sexes, divided into nine groups. The following parameters were estimated: volume of the cerebral hemisphere; volume of the whole BLC and of particular BLC nuclei; neuronal density and total number of neurons in these nuclei. Developmental changes in acetylcholinesterase (AChE) activity in the BLC were also examined. The volume of the cerebral hemisphere increased until P30, whereas volumes of nuclei increased for longer--until P90. The density of neurons in all nuclei studied reached the level characteristic for an adult animal at about P30. The total number of neurons in the dorsolateral division of the lateral nucleus (Ldl) stabilized the earliest--between P30 and P60, whereas in the ventromedial division of the lateral nucleus (Lvm), basomedial (BM) and basolateral (BL) nuclei the number stabilized later--between P60 and P90. AChE activity appears minimal in the BLC on P2, reaches a maximum on P30 and then decreases to the level characteristic of an adult animal on P60. AChE activity was greater in BL than in other nuclei in all age groups. Reaching adult AChE activity 1 month earlier than the total number of neurons in the BLC may indicate a role of the cholinergic system in BLC maturation.

The aim of the present study is to follow topographical and morphological changes in the development of the amygdaloid basolateral complex (BLC) in the rabbit. The material consists of 35 brains of New Zealand rabbits of both sexes, divided into 7 age groups (P2-P90). In cresyl violet preparations BLC is already well visible on P2 and is composed of the lateral (divided into dorsolateral and ventromedial divisions), basolateral and homogenous basomedial nuclei. On about the 7th postnatal day it is possible to divide the basomedial nucleus (BM) into dorsal (Bmd) and ventral (BMv) divisions. The topography and subdivisions set on P7 are maintained in further periods of life. The morphology of neurons (shape, dendrites, staining) changes significantly until P21 in all BLC nuclei. Our results indicate that BLC achieves morphological maturity relatively late, which is probably connected with a long creation of emotional memory and regulation of emotional behaviour.

The aim of the present paper is to describe the morphology and topography of the nuclei of the amygdaloid complex in the rabbit. In the current study we also investigated the intensity of the enzymatic reaction for acetylcholinesterase (AChE) in the amygdaloid complex and the morphology of its neurones. Material consisted of 5 brains of adult New Zealand rabbit, stained either with cresyl violet or for AChE activity. Although, as in other mammals, the rabbit amygdala consists of two main nuclear groups (corticomedial and basolateral), it reveals a peculiar morphology pattern, forming a transition structure between those observed in the cat and rat. Especially characteristic is the arrangement of the basolateral complex. Within that the ventromedial division of the lateral nucleus seems to be the largest, while its dorsolateral division--the smallest. The arrangement of the corticomedial complex in the rabbit is similar to both the cat and rat. In the rabbit the highest acetylcholinesterase activity is found in the basolateral nucleus and the nucleus of the lateral olfactory tract. The lowest AChE staining is observed in the cortical and medial nuclei, amygdalohippocampal and anterior amygdaloid areas and intercalated masses.