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August Krogh (1874-1949) was amongst the most influential physiologists in the first part of the 20th century. This was an era when physiology emerged as a quantitative research field and when many of the current physiological disciplines were defined; Krogh can rightfully be viewed as having introduced comparative physiology, epithelial transport and - together with Johannes Lindhard - exercise physiology as independent disciplines. With a unique ability to design and construct equipment, Krogh could address novel questions in both human and animal physiology with unprecedented precision. Krogh would characteristically focus on a given physiological problem over a couple of years, delineate the focal mechanisms, provide a solution to the major problems, and then move onto new academic ground. For each of his major research areas (respiratory gas exchange, capillary function, osmoregulation), he wrote comprehensive books or monographs that remain important resources for scholars today, and he engaged in the writing of physiology textbooks for the Danish high school. Krogh's research appears to have been driven by curiosity to understand how animals (including humans) work, but he did not hesitate to apply his insight to societal and clinical problems throughout his long academic career., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Livestock models have contributed significantly to biomedical and surgical advances. Their contribution is particularly prominent in the areas of physiology and assisted reproductive technologies, including understanding developmental processes and disorders, from ancient to modern times. Over the past 25 years, biomedical research that traditionally embraced a diverse species approach shifted to a small number of model species (e.g. mice and rats). The initial reasons for focusing the main efforts on the mouse were the availability of murine embryonic stem cells (ESCs) and genome sequence data. This powerful combination allowed for precise manipulation of the mouse genome (knockouts, knockins, transcriptional switches etc.) leading to ground-breaking discoveries on gene functions and regulation, and their role in health and disease. Despite the enormous contribution to biomedical research, mouse models have some major limitations. Their substantial differences compared with humans in body and organ size, lifespan and inbreeding result in pronounced metabolic, physiological and behavioural differences. Comparative studies of strategically chosen domestic species can complement mouse research and yield more rigorous findings. Because genome sequence and gene manipulation tools are now available for farm animals (cattle, pigs, sheep and goats), a larger number of livestock genetically engineered (GE) models will be accessible for biomedical research. This paper discusses the use of cattle, goats, sheep and pigs in biomedical research, provides an overview of transgenic technology in farm animals and highlights some of the beneficial characteristics of large animal models of human disease compared with the mouse. In addition, status and origin of current regulation of GE biomedical models is also reviewed.

Although placental diversity in mammals received growing attention in the 1600s through the early 1800s, placentation was not documented in reptiles until the mid-19th century. In his classic 1855 study on a viviparous lizard, Cesare Studiati (University of Pisa) described a structural/functional arrangement of fetal and maternal tissues that meets contemporary criteria for recognition of placentation. Through the fortuitous selection of a highly placentotrophic species, Chalcides chalcides, Studiati recognized the functional role of placental tissues in provision of oxygen as well as nutrients. Although Studiati worked in a pre-evolutionary milieu and without the benefits of histological techniques, his findings revealed that viviparous reptiles could exhibit placental specializations that paralleled those of mammals. Accordingly, his classic paper initiated a highly productive body of research that has continued to the present and highlighted specializations of a species that has figured importantly in placental research., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Marcello Malpighi (1628-1694) was an Italian scientist who made outstanding contributions in many areas, including the anatomical basis of respiration in amphibia, mammals, and insects and also in the very different fields of embryology and botany. He was one of the first biologists to make use of the newly invented microscope and is best known as the discoverer of the pulmonary capillaries and alveoli. However, he also discovered the spiracles and tracheae that enable respiration in insects. His studies of the embryology of the chicken were far ahead of his time; he then turned to the anatomy of plants, where he made important contributions. Indeed, in some articles Malpighi is referred to as the father of embryology and in other publications as one of the fathers of plant anatomy. His work on the lung was chiefly carried out on the frog; he referred to this animal as the "microscope of nature" because it allowed him to see structures that were not visible in larger animals such as mammals. He also argued that nature undertakes its great works in larger animals after a series of attempts in lower animals. For breadth of interest, innovation, and productivity, it is not easy to think of his equal in the field of life sciences.

This short review traces the history of in vitro experimental methods that have been used to help elucidate the ion transport mechanisms of teleost fish gills. It begins with an isolated gill preparation published by Denis Bellamy in 1961 and progresses through many different approaches and concludes with current techniques. Among them are perfused gill arches, primary cultures of gill epithelia, isolated opercular skin preparations, whole embryos in vitro, the yolk-ball technique, dissociated gill epithelial cells, vibrating microprobe and scanning ion-selective microelectrodes; currently all are combined with molecular biological techniques. Each new approach brought new findings but is subject to certain limitations and each has contributed significantly to this important subfield of comparative physiology., (Copyright 2009 Elsevier Inc. All rights reserved.)

We briefly summarize the history of the rise of comparative physiology in China, the research work focused on by domestic and international counterparts in the field of comparative physiology of China, and international academic exchange and collaboration during this period. We also introduce some of the interesting model systems used in past and current research. This paper is based on documents in historical materials such as the proceedings of the 1st (August 1988) to 6th (October, 2007) Comparative Physiology Academic Session of the Chinese Association for Physiological Sciences, collected physiological works in commemoration academic papers of the 70th (1926-1999) and 80th anniversary of the Chinese Association for Physiological Sciences (1926-2006), CBP and the Physiology History of China, and the authors' own research experience.

Research and teaching activities are of Academician A.N. Severtsov are briefly considered. His scientific heritage is shown to be based on the extensive comparative morphological data on lower vertebrates. The concepts of phylembriogenesis and biological progress elaborated by A.N. Severtsov did not lost their importance as a theoretical and methodological background of the evolutionary morphology as a specific field of zoology dealing with regularities and mechanisms of morphological evolution. Their exploration is of great potential in developments of both epigenetic theory of evolution and particular phylogenetic reconstructions.

This review explores the emergence of Comparative Medicine in the late 19th Century as 'the medicine of the future', its failure to realise these expectations during the 20th century as it became increasingly equated with laboratory animal models of human disease, and explains why there is now an unprecedented opportunity for this latent potential to be fully realised. Comparative medicine no longer rests on apparent similarities between disease mechanisms in different species but on the rapidly maturing ability to relate these similarities to a remarkably rich shared genetic heritage. In the United Kingdom, the creation of the new Medical Research Council Comparative Clinical Science Panel, once securely funded, will provide the infrastructure and strategic focus to foster comparative clinical research, encouraging collaboration between veterinary and human medicine and between investigators in institutes and in practice. This will generate the necessary evidence base for veterinary practice, raise the standard of veterinary research, broaden the horizons of human medicine and create real opportunities for veterinary surgeons to reconcile research with practice. The review explores the broad scope of the science which will flourish in this new environment and examines specific areas in greater depth as examples, notably multifactorial disease such as hypertension and diarrhoea, also aspects of comparative endocrinology and oncology, with emphasis on the growing power conferred by comparative molecular genetics.

Peter Hochachka was one of the most creative forces in the field of comparative physiology during the past half-century. His career was truly an exploratory adventure, in both intellectual and geographic senses. His broad comparative studies of metabolism in organisms as diverse as trout, tunas, oysters, squid, turtles, locusts, hummingbirds, seals, and humans revealed the adaptable features of enzymes and metabolic pathways that provide the biochemical bases for diverse lifestyles and environments. In its combined breadth and depth, no other corpus of work better illustrates the principle of "unity in diversity" that marks comparative physiology. Through his publications, his stimulating mentorship, his broad editorial services, and his continuous-and highly infectious-enthusiasm for his field, Peter Hochachka served as one of the most influential leaders in the transformation of comparative physiology.

Thomas H. Maren studied carbonic anhydrase (CA) for half a century, venturing into all aspects of this powerful enzyme from active site chemistry to clinical medicine. He was a keen proponent of comparative physiology to illuminate basic principles of the chemistry and biology of CA and spent 47 summers at the Mt. Desert Island Biological Laboratory (MDIBL) studying many non-mammalian species. Following the venerable strategy of selecting the right creature to explore a particular question, Maren derived important insights into the role of CA in ion transport, acid-base regulation and gas exchange. Using the fact that tissue CAs are expressed variably in different species, and that these animals differ in temperature, acid-base status and metabolic rate, he defined the contributions of un-catalyzed and catalyzed CO(2) reactions in many physiological processes. Often this strategy simplified a problem and offered answers not easily obtainable in mammals. As examples, he verified the primary role of HCO(3)(-) as lead ion in CSF formation in fish and extended this to mammals. Using marine fish whose kidneys have very little CA, he uncovered mechanisms of acid-base transfer independent of CA that help to explain why CA inhibition does not lead to total bicarbonate depletion.

This article reviews the roots of comparative medicine and argues that during the 20th century it failed to realise its full potential. New opportunities arise from the growing availability of precise, minimally invasive, clinically compatible techniques, which enable us to benefit from the availability of spontaneous analogues of human disease in animals. Particularly with multifactorial diseases, these offer a unique blend of authenticity and acceptability. To realise the full benefits to both animals and humans, we need much closer alignment of human and veterinary clinical medicine., (Copyright 2000 Harcourt Publishers Ltd.)

The paper substantiates the point of view that the first step in the evolution of osmoregulation in vertebrates involved development of water-impermeable epithelium which depended on specific distribution of aquaporins in plasma membranes, secretion of autacoids, formation of water-impermeable cell contacts with a high electrical resistance. Migration of vertebrates to the land was associated with appearance of the ability to regulate osmotic permeability of epithelium in a number of organs involving vasotocin and other pituitary hormones, insertion of aquaporins into the luminal plasma membrane. Enhancement of the renal role in the water-salt balance, intensification of the kidney function was due to a rise in renal circulation, glomerular filtration rate, and tubular reabsorption which, despite the increase in the energy expenditure, provided for an obvious enhancement of the renal work efficiency in maintaining the constancy of the internal medium. Colonisation of desert regions became possible in birds and mammals due to development of the system of urine osmotic concentration. Unlike the accepted point of view that this depended on the appearance of Henle's loops, the statement is substantiated that the leading role in this process is played by differentiation of the kidney into the cortex and medulla, as at our Laboratory nephron loops similar to Henle's loop have been revealed in the lamprey. In the vertebrates, the evolution shifted from the polyorgan to mono-organ type of osmotic homeostasis maintenance, with the leading role of the kidney in maintaining physico-chemical constants of the internal medium fluids.

This article offers the reader two letters from Tommaso Frosini to Francesco Redi of 10 and 21 may 1681 in which important chapters of Giovanni Alfonso Borelli's masterpiece, De Motu Animalium are summarized. The commentary indicates the early circulation of Borelli's work in Florence and the special stress that Francesco Redi laid on it.

Since Rubner established in 1883 the "surface law", the basal metabolic rate (kcal/24 h) is expressed per square meter of body surface. This so-called biological law has been extrapolated to the standardization of several other functions as, for instance, to variables of the cardiovascular, respiratory and renal systems, which may lead to erroneous conclusions. The present paper is an attempt to establish, by means of the dimensional analysis and one of the theories of biological similarity, an allometric indexation procedure, which yields mass-independent numbers (MIN) for all functions which can be defined by means of the MLT-system of physics (M = mass; L = length; and T = time).