Extravascular circulation in the pituitary of Mugil cephalus (Teleostei)

Summary Extravascular circulation in the pituitary of Mugil cephalus was investigated by injecting live fish with horseradish peroxidase and studying the distribution of the enzyme in the gland. The principal components of the extravascular circulatory system are the pericapillary spaces, and, arising from them, the interlobular and circumhypophyseal spaces. Extensions of these spaces penetrate the glandular parenchyma of the pars distalis, where they merge with pericellular spaces. In the neurohypophysis, pericapillary spaces are connected to the periaxonal spaces.Capillaries penetrating from the proximal neurohypophysis into the pars distalis are accompanied by neurosecretory axons. These axons form a mass of tissue which is limited near the capillaries by the pericapillary spaces and near the adenohypophysis by the interlobular spaces. Toward the interior of the adenohypophysis the amount of nervous tissue accompanying the capillaries progressively diminishes, thus reducing the distance between pericapillary and interlobular spaces. Within the pars distalis, the neurosecretory axons accompanying the capillaries are sparse, and the secretory and stellate cells are mostly located directly adjacent to the pericapillary spaces. In the neuro-intermediate lobe, interlobular spaces outline the neuro-adenohypophyseal boundary.The relationship between extravascular spaces and hormone-secreting cells varies in the different regions of the adenohypophysis depending upon the type of neurosecretory innervation in the respective region. In the regions of prolactin and gonadotropin cells, where neurosecretory axons are in direct contact with the secretory cells, the hormone-secreting and stellate cells are adjacent to the pericapillary spaces. In the regions of ACTH and STH cells, secretory and stellate cells are found adjacent to the interlobular spaces, which are interposed between the cells and the neurosecretory axons.Abbreviations AH adenohypophysis - CH circumhypophyseal - DNH distal neurohypophysis - HRP horseradish peroxidase - NH neurohypophysis - NS neurosecretory - PD pars distalis - PI pars intermedia - PPD proximal pars distalis - RNH rostral neurohypophysis - RPD rostral pars distalis This research was supported by a grant from the National Council for Research and Development, Israel, and the GKSS Geesthacht-Tesperhude, Federal Republic of Germany     

Fine structure of the stellate cell in the pars distalis of the lizard, Anolis carolinensis

The stellate cell in the pars distalis of Anolis carolinensis has been studied with the electron microscope. This cell type is characterized by the lack of secretory granules, and it possesses elongate processes that insert between secretory cells. Few cytoplasmic filaments are present in these processes, and desmosomes linking them to adjacent stellate cells or to secretory cells are seen infrequently in control animals. Stellate cells are often encountered in the caudal half of the pars distalis, but they are less commonly found in the rostral half. In animals undergoing thyroidal depression, thyroidectomy cells arise in the caudal pars distalis. Concurrently, stellate cells of that region hypertrophy and exhibit increased numbers of desmosomes, complex intercellular junctions, and micropinocytotic vesicles. Injected horseradish peroxidase penetrates the intercellular spaces, enters the micropinocytotic vesicles, and is transported to the interior of the stellate cell. It is suggested that stellate cells in Anolis under certain conditions may transport materials between the bloodstream and secretory cells.     

Immunocytological study on the differentiation of chick and quail adenohypophysis epithelial rudiments, grafted or cultivated in vitro: evidence for polypeptidic hormones

Epithelial rudiments of adenohypohysis were removed from chick and quail embryos between days 3 and 5 of development. Chick rudiments were grafted for 11--13 days onto the chorioallantoic membrane of decapitated chick embryo hosts. Quail rudiments were cultivated in vitro for 6 days. Both grafted and cultivated Rathke's pouches differentiated into adenohypophyseal tissue. The adenohypophyseal tissue cultured on chorio-allantoic membrane exhibited cells reacting with the following immune sera: anti-beta-(1--24)ACTH, anti-alpha-(17--39)-ACTH, anti-alpha-endorphin, anti-beta-endorphin and anti-beta-LPH, which also gave a positive reaction when applied to adenohypophysis of corresponding age which had differentiated in situ. In situ, corticotrophs were located exclusively in the cephalic lobe of adenohypophysis. Therefore, the differentiation of corticotrophs in the whole graft, i.e., from both cephalic and caudal lobes of Rathke's pouch, showed that the cells of the caudal lobe, or at least some of them, were uncommitted when the rudiment was removed. In vitro, tissue derived from Rathke's pouch contained cells reacting with antibodies to beta-(1--24)-ACTH, alpha-(17--39)-ACTH, and beta-LPH, as did adenohypophysis from quail embryos of corresponding age (9--10 days), differentiated in situ. The differentiation of quail Rathke's pouch in vitro corroborates that differentiation can occur without influence from hypothalamus and, moreover, shows that at least some kinds of cells can differentiate without influence exerted by any other encephalic factors, and in the absence of mesenchyme. The question arises whether fibroblastic cells derived from Rathke's pouch cells act as feeder-cells and/or secrete some factors promoting differentiation.     

Regulation of ion transport in hypophysial pars intermedia follicular cell monolayers

We have previously reported that cultured monolayers of folliculo-stellate cells (FC) of adenohypophysial pars tuberalis (PT) and pars distalis (PD) origin express morphological and electrical properties typical of ion and fluid transporting epithelia. The objective of the present study was to examine whether cells expressing similar transport properties exist also in the pars intermedia (PI), an area of the adenohypophysis very poorly vascularized, where a cell type expressing such functions would be expected to play an especially significant role in the local regulation of the interstitial fluid content and circulation. Enzymatically and mechanically dispersed bovine pars intermedia fragments yield monolayers of polygonal, contact inhibited cells which rapidly develop domes. Such cells exhibit morphological features and growth properties very similar or identical to those expressed by cells previously identified af FC cells in PD and PT cultures. Similarly to their counterparts in the PD and PT, the PI FC display a potential difference and a resistance when mounted in Ussing chambers. Isoproterenol, prostaglandin E2, bradykinin and lysine vasopressin are able to stimulate active ion transport across FC monolayers. These data indicate that the PI contains ion transporting FC and suggest important local regulatory functions for these cells.     

Embryonic development and secretory differentiation in the pars tuberalis of the mouse hypophysis

Summary The pars tuberalis (PT) of the mouse, like that of other mammals, consists mainly of glandular cells rich in glycogen and peculiar to this lobe. In the mouse, the glandular cells are characterized by large, dense secretory vesicles (up to 300 nm in diameter), the abundance of which indicates a marked secretory activity. The PT develops from a distinct antero-ventral area of Rathke's pouch. The border between the anlagen of the PT and the pars distalis is formed by Atwell's recessus which represents the access for the vessels afferent to the pars distalis. The pedicle of Rathke's pouch is incorporated into the PT anlage, thus contributing to its formation. The entire PT anlage is characterized by glycogen accumulation from the commencement of its formation and persisting in the adult tuberal lobe. Secretory differentiation of the glandular cells of the PT occurs at day 12 of gestation, preceding that of all other adenohypophysial cell types. The secretory features of these cells (development of ergastoplasm and Golgi apparatus, abundance of dense secretory vesicles) appear at an early stage of the embryonic life (14 days) comparable to those of mature cells. These results confirm earlier observations in the foetal rat where hypophysial secretion also begins in the PT. The existence of peculiar glandular cells speaks in favour of a specific but still unknown function of the PT during foetal and adult life.This work is dedicated to Professor F. Stutinsky     

The differentiation of prolactin cells in an organ culture of chick embryo adenohypophysis

We have studied differentiation of prolactin cells in explants of cephalic and caudal parts of Rathke's pouch of 4.5 day and 5.5 day old chick embryos after their incubation in vitro lasting for 7-8 days. Indirect immunofluorescence using an antiserum against bovine prolactin was used to detect prolactin cells in the cultures. Differentiation of prolactin cells was detected regularly in explants of the cephalic lobe of the adenohypophysis anlage in 5.5 day old embryos; under certain growth conditions prolactin cells were found in explants of the same lobe in 4.5 day old embryos. Prolactin cells were either absent or found in small numbers in cultures of the caudal part of adenohypophysis of 5.5 day old embryos. Our results provide evidence for the appearance of the committed precursors of prolactin cells in the Rathke's pouch at late stages of its formation and for their regional localization in the cephalic part of the anlage. This localization is in correspondence with the distribution of differentiated cells of this type in definitive adenohypophysis.     

Morphology and immunocytochemistry of the turtle pituitary gland with special reference to the pars tuberalis

Summary Examination of pituitaries from young and adult turtles representing four families, reveals that in addition to the abundant juxtaneural pars tuberalis (JuxPT) found in this class of reptiles, there is generally a substantial amount of pars tuberalis (PT) tissue closely associated with the pars distalis (PD). The PT forms a cortical layer especially conspicuous around the anterior tip of the PD in some species (Trionyx, Kinosternon, Sternotherus), or it forms a thick dorsal layer of tissue irregularly extending onto the sides of the PD in others (Pseudemys, Chrysemys, Lepidochelys, Chelonia).Immunocytochemical studies using unlabelled second antibody and peroxidase-antiperoxidase reveal that in turtles of all ages, the PT tissue allied with the PD (the PTinterna) is composed primarily of cells containing glycoprotein hormones (FSH, LH and TSH), especially the gonadotropins. The juxPT, however, consists mainly of secretory cells unstained by the antisera tested and includes only a small number of gonadotropes and thyrotropes. Although usually widely distributed in the testudinate adenohypophysis, the great majority of gonadotropes and thyrotropes present in the hatchling are in the PTinterna. It is probable that a concentration of these cells in the PTinterna is widespread among vertebrates.In all turtles examined, lactotropes occur principally in the anterior and ventral part of the PD proper; somatotropes are posterior and dorsal. Corticotropes are concentrated as the lactotropes in the anterior PD, but some are also scattered throughout the posterior half of the gland. Lactotropes, corticotropes, and with a few exceptions, somatotropes, do not occur in PT tissue in the turtle.We are grateful to Drs. Harold Papkoff and J.C. Ramachandran of the Hormone Research Laboratory of the University of California in San Francisco for their generous gifts of several antisera and to Dr. Ludwig Sternberger for the peroxidase-antiperoxidase used in this study. Thanks are also given to Phyllis Thompson for assistance with the illustrations and to William Rainey, David Owen and John Cadle for specimens that they made available. Use of the facilities of the Electron Microscope Laboratory of the University of California at Berkeley is gratefully acknowledged, including use of the JEOL-JEM 100CX transmission electron microscope purchased under National Science Foundation Grant Number PCM-7821561. This work was supported by NSF grant PCM-7812470 to PL     

A typology of the gnathostome adenohypophysis with some emphasis on its gonadotropic function.

Recent publications show that the average gnathostome adenohypophysis consists of four parts and contains six morphological cell types. Histophysiological and immunocytochemical data prove the secretion of one or two gonadotropins by one type of basophils that in numerous species in characterized by the presence of large globules besides secretory vesicles. The existence of a second type of gonadotropin secreting cells remains doubtful. Thyrotropin is produced by a separate type of basophilic cells, prolactin by erythrosinophils of the rostral pars distalis, and somatotropin by orangeophils of the proximal pars distalis. At rostral and caudal places of contact with the neurohypophysis, cells are concentrated that may be lead-haematoxylin-positive, and produce a protein consisting of peptides with hormonal and opiate activities. Among the hormones secreted by these cells, situated in the pars distalis and the pars intermedia, are corticotropin and melanotropin respectively. The factors that cause the differentiation of the primordium of the adenohypophysis are almost entirely unknown.     

Immunohistochemical Study of Adenohypophysial Cells During Embryonic Development in the Reptile Chalcides chalcides (Squamata, Scincidae)

The immunohistochemical avidin-biotin complex method was used to study hormone-producing cells in the adenohypophysis of the skink Chalcides chalcides during embryonic development. In Chalcides, the formation of Rathke's pouch was evident between stages 28 and 30 of embryonic development. The adenohypophysial cells begin to differentiate before the morphological development of the gland was complete. At stage 29, few corticotropic cells were present only in the dorsal face of Rathke's pouch. No other immunoreactive cell type was revealed at this stage. At stage 32, the hypophysis had developed to a great extent though it was not yet elongated in a cephalic-caudal direction. At this stage, the corticotropic cells appeared more numerous and well differentiated in the rostral pars distalis and in the pars intermedia. Melanotropic, somatotropic and gonadotropic cells appeared simultaneously, with the same distributions as in the adult skink. At stage 34, the first thyrotropic cells appeared in the pars distalis but also in the pars intermedia, whereas rare prolactin cells were observed only at stage 35 in the medial pars distalis. Between stages 36 and 38, the gland was developed in the cephalic-caudal direction and all the cell types were completely differentiated with an evident increase in the number of prolactin cells. In embryos close to birth (stages 39-40), the hypophysis and the adenohypophysial cells were already similar to those of the adult animal.     

A light and electron microscopic study of the pre- and postnatal development and secretory differentiation of the pars tuberalis of the rat hypophysis

Summary The development of the pars tuberalis was studied in the rat fetus from 13 days of gestation to 6 weeks after birth. After the closure of Rathke's pouch, the pars tuberalis anlage is clearly distinguishable from the anlagen of the partes intermedia and distalis. It comprises the entire basal portion of the adenohypophysial anlage; the limit between the anlagen of the pars tuberalis and the pars distalis is defined by Atwell's recess, i.e. the pathway taken by the hypophysial vessels coming from the vascular plexus of the median eminence.At 14 days the pars tuberalis cells are characterized by the presence of glycogen which persists in the adult. Their secretory differentiation (elaboration of granules with a diameter of 100–120 nm) is obvious at 15 days of gestation. It therefore, clearly precedes that of the other hypophysial cell types. Its functional differentiation takes place well before its adhesion to the primary vascular plexus of the portal system. Cystic formations appear just before birth in the pars tuberalis, much later than those of the pars distalis.These observations on the development of the pars tuberalis, together with previous observations on the adult PT in various species, showing that the specific glandular cells of the pars tuberalis are cytologically different from all known adenohypophysial cell types, seem to indicate a specific endocrine function of this lobe.     

Fine structure of the adenohypophysis in immature sockeye salmon,Oncorhynchus nerka

Summary The ultrastructure of the secretory cells of the adenohypophysis of juvenile sockeye salmon was investigated. Pituitary glands were collected from immature fish transferred experimentally to sea water and subsequently returned to fresh water. The rostral pars distalis contained three cell types: ACTH cells, prolactin cells, and non-secretory cells. The prolactin and non-secretory cells were joined together in the form of follicles by desmosomes and they both had cilia and microvilli projecting into the follicle lumen. Various follicular structures such as lumen, multivesicular structures, and peripheral basement membrane are discussed as possible sites of prolactin cell granule release. The columnar ACTH cells were found at the junction of the rostral pars distalis and the neurohypophysis. The cytoplasmic granules in these cells were characteristically separated from their limiting membrane by a clear space. Multivesicular structures were also found in association with this cell type. The caudal pars distalis also contained three cell types: one acidophil (putative somatotrop) and two basophils (putative thyrotrops and gonadotrops), all of which were similar to those described in adult fish. The pars intermedia contained only one cell type. They appeared to be active cells and were characterized by containing membrane-bounded granules similar to those found in the ACTH cells. Changes in ambient salinity had no apparent effect on any cell type described.The work was supported by a grant in aid of research from the National Research Council of Canada. We wish to thank Mr. R. Lindsay, Mr. C. Cooper, and Mr. G. Longworth for their technical assistance. We would also like to thank Mr. S. Killick of the International Pacific Salmon Fisheries Commission for his assistance in the collection of fish and Dr. H. Cook for his helpful discussion of the project. This paper is No. 058 in the University of Guelph Migration Series.     

An electron microscopic study of stellate cells and cavities in the pars distalis of frog pituitary

Stellate cells in the pars distalis of adult Rana ridibunda were observed electron microscopically under normal and experimental conditions (TRH injection). The stellate cells have lengthy processes extending into the intercellular spaces between the secretory cells and scanty cytoplasm surrounding the nucleus. Occasional desmosomes link stellate cells to adjacent secretory cells. In the pars distalis of animals injected with thyrotropic-releasing hormone (TRH), the stellate cells form large cavities (2-6 mum) filled with heterogeneous material. Their cytoplasm contains well-developed Golgi complexes and some lysosomes; these are the principal morphological alterations as compared to those observed in control animals. It is suggested that stellate cells could play an active role in addition to providing a structural framework for the pars distalis.     

Light and electron microscopic studies on the pars intermedia of the chameleon

Summary The neurointermediate lobe of the hypophysis in the Chameleon (Chamaeleo dilepis) was examined with light and electron microscopic methods, with special reference to the cytology of the pars intermedia (PI). The PI is the largest lobe of the hypophysis consisting of (1) dark cells with secretory granules ranging from 200–600 nm; (2) light cells, far fewer in number, containing granules 150–300 nm in diameter; (3) stellate, non-secretory cells. The secretory cells abut onto the perivascular basal lamina of the capillary sinusoids while their apical part borders an intercellular space. This surface of the cells often bears a cilium. The granules arise from the Golgi cisternae while small detached vesicles are found between circumscribed sites of the cell membrane and the Golgi apparatus. No nervous elements were found in the pars intermedia and it is assumed that the regulation of this lobe is purely humoral. This is supported by the presence of three types of nerve terminals in the pars nervosa: (a) terminals with large secretory granules and small vesicles; (b) terminals with dense-core vesicles and small vesicles; (c) terminals with small vesicles only. All of these are secretory as indicated by the presence of the synaptic semidesmosomes formed with the perivascular basal lamina.I would like to thank Mr. W.N. Newton for his skill and aid in all aspects of this work, Mr. A. Ansary for expert photographic assistance and the Central Pathology Laboratory, University of Dar es Salaam, for the electron microscopic facilities provided. Research sponsored by the University of Zambia Grants J02-18-00 and Medic 74/6     

贝氏高原鳅脑垂体显微结构观察

贝氏高原鳅的垂体由神经垂体和腺垂体构成,属于背腹型,但神经垂体稍偏向背部.腺垂体从前到后又依次分为前外侧部(RPD)、中外侧部(PPD)和中间部(PI).前外侧部由ACTH细胞和PRL细胞组成,中外侧部由GH细胞和大小两种嗜碱性细胞组成,中间部分布有MSH细胞和另一种嗜碱性细胞.神经垂体分枝丰富,遍布于腺垂体的各个部分,在中间部尤为丰富.垂体内血管发达.     

Demonstration of Stellate Cells of the Pars Intermedia of the Pituitary Gland Using a New Silver Impregnation Technique

The pars intermedia of the pituitary gland in the rat and other species contains, in addition to secretory cells, stellate cells first characterized by using electron microscopy. The distribution and relationships of these cells is difficult to assess at the ultrastructural level. We have developed an ammoniacal silver nitrate method for stellate cells of the pars intermedia. Staining is carried out in 15 µl;m sections of buffered formalin fixed, paraffin embedded pituitaries. This method shows that in the rat pars intermedia, stellate cells showing numerous cytoplasmic projections are abundant in, and evenly distributed throughout, pars intermedia lobules.     

Immunohistochemical localization of adrenocorticotropin and melanocyte stimulating hormone in pars intermedia of rat hypophysis

Summary The sites of production of adrenocorticotropin (ACTH) and melanocyte stimulating hormone (MSH) are studied by the immunoglobulin-peroxidase bridge technique, using antisera prepared against synthetic porcine 1–24 and 17–39 ACTH, and bovine MSH on the rat adenohypophysis. Presence of ACTH all over the pars intermedia (PI) is indicated by staining with antisera _p 1–24 and _p 17-3-9 ACTH. There are darkly stained ACTH cells in the PI and pars tuberalis (PT), similar to those in the pars distalis (PD). With higher dilutions of the ACTH antiserum, staining intensity disappears or reduces markedly in majority of the PI cells, whereas, the ACTH cells in the PI, PD and PT do not vary much in their staining intensity. Therefore, it is concluded that majority of the PI glandular cells (light glandular and dark cells) contain less corticotropin than the ACTH cells. From these observations, it seems to me that the major amount of corticotropin is supplied by the ACTH cells of the PD, PI and PT, and less by the light glandular and dark cells of the PI. The antiserum is ineffective after absorption, so the staining reaction appears to be specific for _p 1–24 and _b 17–39 ACTH.Presence of MSH all over the PI is indicated by staining with antisera to bovine MSH. Majority of the PI cells are highly stained even with higher dilution of the antiserum. The unstained cells in the PI seem to be ACTH cells and/or marginal cuboidal cells. The antiserum was ineffective after absorption, so the staining reaction appears to be specific for _b MSH.Control over the PD corticotropin through the median eminence portal circulation and the PI and PT control through nervous system is also discussed.This study was supported by MRC of Canada Grant nos. MA-3759, and MA-5160.The author gratefully wishes to thank Drs. P. Desaulles and W. Rittel (CIBA, Basle, Switzerland) for the synthetic _p 1–24 ACTH and _b MSH, Dr. R. F. Phifer for _p 17–39 ACTH, and Dr. S. S. Spicer for providing samples of rabbit anti-porcine 17–39 ACTH and anti-human ACTH sera, Drs. George Sétáló and Paul Nakane for their valuable advice. He also acknowledges the help of Mr. Shankar Nayak to prepare the antisera and the skilful technical assistance of Miss. Elise Poiré.     

Distribution of 3H-thymidine in the postnatal hypophysis of the C57BL mouse

The distribution of cells labelled with 3H-thymidine was determined autoradiographically in the adenohypophysis and neurohypophysis of the C57BL mouse during postnatal phases ranging from the newborn to 24 days of age, as well as in the adult. In the newborn, labelled cells are scarce in the neurohypophysis but common in the adenohypophysis. The neurohypophysis shows a surge in labelling at 5-9 days, with a sharp decline thereafter. In the adenohypophysis, labelled nuclei are scarce in the pars tuberalis after 19 days, whereas the pars intermedia and pars distalis continue to show labelled cells. In the pars distalis, at all phases, label occurs in the marginal cells along the hypophysial cleft as well as in deeper-lying cells representing follicular cells. In the adult, follicular cells are more commonly labelled relative to other cells of the hypophysis.     

Histochemical and cytochemical demonstration of Ca++-ATPase activity in the stellate cells of the adenohypophysis of the guinea pig

The histo- and cytochemical localization of Ca++-ATPase activity in the adenohypophysis of the guinea pig was studied utilizing a newly developed method (Ando et al. 1981). An intense reaction was observed in the wall of the blood vessels and between non-secretory cells (stellate cells) and endocrine cells of the pars distalis. Under the electron microscope the Ca++-ATPase reaction product was located extracellularly in relation to the plasmalemma of the stellate cells. This reaction was dependent on Ca++ and the substrate, ATP, and reduced by the addition of 0,1 mM quercetin to the standard incubation medium. Preheating of the sections before incubation completely inhibited the enzyme activity. When Mg++ in different concentrations were substituted for Ca++ in the incubation medium the reaction was always reduced. Both Ca++ and Mg++ in the incubation medium also reduced the reaction. The plasmalemma of the endocrine cells contains no demonstrable amount of Ca++-ATPase activity. The function of the Ca++-ATPase activity is discussed in relation to the regulation of the extracellular Ca++ concentration which seems to be important with respect not only to the secretory process of the endocrine cells but also to the metabolism of the adenohypophysis.     

Pituitary cytology of the freshwater teleost Anabas testudineus (Bloch)

In the pituitary of A. testudineus the rostral pars distalis (RPD), proximal pars distalis (PPD) and pars intermedia (PI) are arranged in a rostro-caudal axis. The rostral neurohypophysis (NH) extends dorsal to the pars distalis, while the caudal part vertically penetrates into the PI and ramifies in its component. The RPD mainly consists of erythrosinophils and PgH-positive cells which are comparable to the lactotropes and corticotropes mentioned in the literature. In the nonbreeding season, acidophils are the predominant cells of the PPD and are largely confined to its dorsal aspect. The two types of cyanophils present in the PPD could not be differentiated with the various techniques used in this study. However, those cyanophils which increase in number and are active during the spawning season may be the gonadotropes, while those which are cytologically inactive may be the thyrotropes. The pars intermedia consists of PAS+ and PhH+ cells. Trichrome and tetrachrome staining techniques revealed the presence of acidophils, cyanophils and amphiphils in the PI.     

乌龟脑垂体显微及其腺垂体超微结构的研究

乌龟脑垂体由柄形神经垂体和椭圆形腺垂体两部分组成,神经垂体位于腺垂体后部上方呈背腹型排列。神经垂体中神经叶不发达,腺垂体分为远侧部和中间部,特殊空泡结构成为垂体门脉系统的特征。远侧部细胞分为嗜酸性细胞、嗜碱性细胞和嫌色细胞3种。通过透射电镜观察,腺垂体远侧部主要有5种分泌激素细胞:即生长激素(GH)分泌细胞、催乳激素(PRL)分泌细胞、促甲状腺激素(TSH)分泌细胞、促肾上腺皮质激素(ACTH)分泌细胞、促性腺激素(GTH)分泌细胞和非分泌类型滤泡-星形细胞(FS)。生长激素分泌细胞核大、分泌颗粒少的特征成为乌龟与其他动物最大的区别,可能与乌龟具有生长慢、寿命长的生物学特性有关。