摘要:

The morphology of the tapetum lucidum of the grey seal (Halichoerus grypus) has been studied by light and electron microscopy. The reflective layer in this species is a tapetum cellulosum situated in the choroid and covering the entire effective fundus. Posteriorly the tapetum is composed of 30–35 layers of flattened polygonal cells. This number gradually declines to 15–20 layers in the extreme periphery. Near the retinal epithelial layer the tapetal cells are larger and more regular (brick-like) in arrangement whereas further from the retina the tapetal cells become more irregular in outline and more widely separated by collagen fibrils and connective tissue cells. In this outer region the tapetal cells are gradually replaced by melanocytes of the choroid. Within the tapetal cells a few mitochondria and profiles of smooth endoplasmic reticulum are scattered peripherally while the majority of the cell organelles are clustered near the centrally located vesicular nucleus. The dominant feature of the tapetal cells is, however, an accumulation of numerous electron-dense rodlets of presumed zinc cysteine. These rodlets are the reflective material of the tapetum and are arranged with their long axes perpendicular to the incoming light. The orientation of these rodlets is usually uniform within each tapetal cell but varies between adjacent cells. The diameter (0.10 µm) and spacing (0.15 µm) of these rodlets is consistent with the principles of constructive interference. Blood vessels penetrate the tapetum at right angles to supply the choriocapillaris which is indented into the amelanotic retinal epithelium to give a flat reflective surface to the ta

ISSN:1422-6405    

DOI:10.1159/000146260

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

This contribution deals with the ultrastructure of the pancreatic nervous system of the dog 14 days and 5 months after bilateral truncal vagotomy. No major ultramorphological changes in the axons or their organelles (vesicles, mitochondria, microtubuli) were observed, and there appeared to be no reduction in the numbers of sympathic and cholinergic axis cylinders (material fixed in glutaraldehyde and potassium permanganate) or neurocellular contacts.

ISSN:1422-6405    

DOI:10.1159/000146261

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

Forty 1-week-old Sprague-Dawley rats were divided into 4 groups of 10 animals each. Five rats of each group served as the controls, and another 5 were given weekly intraperitoneal injections of 20 mg cyclophosphamide (CTX, Endoxan, Cytoxan) per kg of body weight. The animals of each group were sacrificed either at 1 3, 5, or 7 weeks after initial intraperitoneal injection of CTX or water. The mandibular condyles of all rats were assayed histomorphometrically for changes on cartilage and bone cells, and other elements. The results showed a decreasing tendency in the thickness of the cartilage layer, the number of prechondroblasts, the number of chondrocytes, the percentage of cartilage matrix, the percentage of hard tissue, the bone surface perimeter, the number of osteoblasts, the number of osteoclasts, and the average number of nuclei per osteoclast in the condyles at 1 or 3 weeks after initial CTX treatment. After 7 weeks of treatment with CTX there was a significant decrease in the thickness of the cartilage layer, the number of prechondroblasts, and the numbers of both osteoblasts and osteoclasts per square millimeter of bone surface in the condyles, when compared with those of the control groups. In addition, after 5 or 7 weeks of CTX treatment there was a significant decrease in the percentage of hard tissue, the number of osteoblasts and the number of osteoclasts. Furthermore, changes in the morphology and size of the bone cells were also observed in all the rats. The reduction of the thickness of the cartilage layer was due mainly to a marked decrease in the* number of proliferative chondrocytes and the percentage of the cartilage matrix. All these findings demonstrated that a treatment of 20 mg CTX per week for 5 or 7 weeks had a cumulative effect which inhibited bone formation and affected both normal mandibular growth and facial profile in the juvenile rats. The cytotoxic effect of CTX also exerted an influence on the mitotic division of bone cells and the trabecular volumetric density of the madibular condyle.

ISSN:1422-6405    

DOI:10.1159/000146262

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

Seven rhodamine-conjugated lectins were utilized to study the distribution of glycoproteins in the developing rat testis and epididymis. In the testis a clear developmental pattern was found in Ley dig cells and the cell boundaries between Sertoli and spermatogenic cells, as well as during acrosome formation. Some of the first degenerating meiotic cells and the apical extensions of the Sertoli cells at the time of spermiation also displayed a characteristic lectin binding. The epididymal differentiation was characterized by an increasing lectin binding of the subapical Golgi zone and apical surface, and intratubular secretion prior to the arrival of sperm. After the accumulation of tubular secretion and sperm some epithelial cells were transformed into narrow (initial segment) and light cells (distal caput, cauda) with a strong affinity for some lectins. These cells appeared to be responsible for the absorption and digestion of tubular material derived from the testis and of surplus secretion and/or sperm structures.

ISSN:1422-6405    

DOI:10.1159/000146263

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

A high incidence of vaginal adenosis-like lesions (ADL, 67%) was found in 30-day-old offspring of ICR/JCLmice given 4 daily subcutaneous injections of 2,000 µg diethylstilbestrol (DES) on days 15–18 of gestation. The prenatally DES-exposed mice and the controls ovariectomized at 10 days of age were given 5 daily subcutaneous injections of 10–4, 10–3, 10–2, 10–1, or 1 µg 17β-estradiol (E2), respectively, starting at 25 days of age. ADL was never observed in the age-matched controls given prepubertal injections of any E2 dose. In contrast, high incidences of ADL (63–100%) were found in the vaginal fornix and upper vagina of 30-day-old DES mice receiving prepubertal injections of 10–3–1 µg E2/day, whereas in DES mice given prepubertal injections of the vehicle alone and a lower daily dose of 10–4 µg E2, incidences were nil and 25%, respectively. Mitotic figures were found in the columnar epithelium with ADL, although the rate was lower than in the ADL-freed stratified epithelium. It is suggested, therefore, that an ovarian hormone (probably estrogen) participates in the prepubertal induct

ISSN:1422-6405    

DOI:10.1159/000146264

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

This study was designed to explain whether the sex-dependent differences in the structure of the thyroid gland of adult male and female rats depend on quantitative or qualitative changes in the thyroid follicular cells. Absolute thyroid gland weight was similar in male and female rats, but its relative weight was markedly higher in females however. Volume fractions of epithelium and stroma were higher and that of colloid lower in male than in female rats and the epithelium/colloid ratio was higher in the males. Also absolute the volumes (in mm3) of epithelium and stroma were higher in the males; the thyroid gland of females contained more colloid. The average volume of a thyroid follicular cell, estimated by stereology, was higher in males than in females, although the thyroid gland contained similar numbers of follicular cells in both sexes. Also, thyroid glands from both male and female rats contained a similar DNA quantity. Results of the present study show that the sex dimorphism in the rat thyroid depends upon a difference in the mean volume of thyroid follicular cells, with males having larger cells than females. However, in both sexes the thyroid gland contains a similar quantity of these cells.

ISSN:1422-6405    

DOI:10.1159/000146273

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

Morphometry was carried out on the luminal epithelium of the rabbit uterus from oestrus to day 21 of pseudopregnancy. This indicated that syncytia increased in size until day 18, after which a rapid reduction occurred with approximate oestrous dimensions being restored on day 21. Involution of syncytia took place in two overlapping stages with reduction in nuclear numbers occurring from day 12 onwards, followed by loss of cytoplasm mainly after day 18. Ciliated cells predominated at oestrus and day 21 but were sparse at other times. When ciliated cells were plentiful, they were concentated on the tops of the mucosal folds.

ISSN:1422-6405    

DOI:10.1159/000146265

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

The neurons of the supraoptic nucleus (SON) in the rat have been analysed by electron microscopy and morphometry, when the secretion of the antidiuretic hormone was fully suppressed by water loading. The water was supplied through a catheter inserted in the external jugular vein for 1.5, 2.5 and 24 h, respectively. The SON was also examined in normal rats and in rats that had been deprived of water for 72 h. The rats were fixed through chronically implanted catheters, so that at the time of fixation, the animal was uninfluenced by anaesthesia and surgery. The morphology of the granular endoplasmic reticulum and the Golgi complex showed that the water load suppressed the synthetic activity and the water deprivation stimulated it. The total volumes of the vasopressin-containing neurosecretory granules (NG) were 1.6, 2.8 and 5.0 · 104 µm3 after a 24-hour water load, in the normal state and after 72-hour water deprivation, respectively. In steady states there was a positive correlation between the secretory activity and the content of NG in the perikaryo

ISSN:1422-6405    

DOI:10.1159/000146266

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

Tibiae from 11-day-old chick embryos, injected with 3H-tetracycline, were autoradiographically analyzed at different stages to localize and study the dynamics of the initial phases of bone mineralization, 3H-tetracycline was localized within newly formed trabeculae, but only at the surfaces of older trabeculae, indicating that the incorporation of tetracycline into bone occurs at active sites of calcification. It takes between 24 and 36 h for injected tetracycline to become stabilized and incorporated into the mineralized matrix. Absence of 3H-tetracycline grains over the osteoblasts suggests a paracellular pathway for incorporation of tetracycline into the mineralizing bone matrix.

ISSN:1422-6405    

DOI:10.1159/000146267

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

The developmental pattern of the bovine fetal large intestine was studied with particular reference to the appearance and decline of the intestinal villi during the fetal period. In the bovine large intestine, the first rudimentary villus and goblet cells were seen in the rectum in a fetus estimated to be 3 months old. By 5–6 months, the goblet cells, absorptive cells in the intestinal crypts, and vacuolated cells in the villi were present along all segments of the large intestine. By 8–9 months, the villi have disappeared from the colon and rectum, epithelial cells no longer contain vacuoles, and absorptive and goblet cell populations are emerging from the crypts. These histological results suggest that development in the bovine large intestine follows a rectocecal gradient and the most distinct turning point during the fetal period is the first disappearance of fetal villi in the rectum of fetuses estimated to be 7 months old. After this stage, the mucous membrane of the colon and rectum matured rapidly before birth. In contrast, the cecum may seem to require further development in perinatal l

ISSN:1422-6405    

DOI:10.1159/000146268

出版商:S. Karger AG    

年代:1986

数据来源: Karger