摘要:

AbstractWe examined the ultrastructural features of postnatal alveolar septal formation in rats from birth to 28 days of age. At birth, the rat lung consists of large saccules with thick walls and cellular interstitium. Interstitial cells have large oval nuclei with scant cytoplasm containing few organelles and scattered lipid droplets. These cells appear to be poorly differentiated mesenchymal cells not engaged in active protein synthesis or secretion. Between 5 and 15 days of age, saccule walls thin and many new alveolar septa form. Two types of interstitial fibroblasts are present: one which appears at the tips of newly formed septa has the characteristics of a myofibroblast and appears to be engaged in synthesis and secretion of elastin; the other fibroblast appears at the base of new septa, is filled with lipid and contains few other cytoplasmic organelles. After 15 days of age, alveolar walls become thinner, few new septa form and interstitial fibroblasts begin to resemble the dormant type of fibroblasts seen at birth. Thus, the process of postnatal alveolarization of lung parenchyma involves differentiation of the interstitial fibroblast and elastogenesis. The factors which control this process, the precise role of elastogenesis in alveolar septal formation, the origin and fate of the lipid filled fibroblast and the ultimate fate of the myofibroblast remain to be determined.

ISSN:0003-276X    

DOI:10.1002/ar.1091920402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY

摘要:

AbstractHuman fetal lung organotypic cultures consisted of epithelial elements (≃40‐100 m̈m in diameter) formed by the reaggregation of single cells from a monodisperse suspension of enzymatically dissociated fetal lung. These elements, termed alveolar‐like structures, were composed primarily of type II alveolar epithelial cells whose apical surfaces bordered the central lumen of the alveolar‐like structure. Pulmonary surfactant secreted by the type II cells was retained within the lumen and accumulated in close association with the epithelium. These characteristics made this culture system an advantageous model for the morphological study of human pulmonary surfactant in vitro. A lipid‐carbohydrate retention procedure which reduced the extraction of tissue components and thus provided improved preservation of multilamellar bodies and tubular myelin surfactant was used in an ultrastructural study of organotypically cultured surfactant. Human surfactant was observed for the first time with most of its structural components intact. In vitro human surfactant was found to be similar to in vivo rodent and non‐human primate surfactant, but with certain differences. Long surfactant tubules were not observed. There were more transformed multilamellar bodies present with more foci undergoing transformation. Each focus contained fewer layers of tubular myelin surfactant than occurs in rodent surfactant. No epiphase‐hypophase areas were observed, only tubular myelin surfactant. In addition, a previously unreported intrasurfactant matrix materia

ISSN:0003-276X    

DOI:10.1002/ar.1091920403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY

摘要:

AbstractDifferent types of human germ cells show unusual features of the nuclear envelope. Spermatogonial nuclei demonstrate two kinds of modifications. The first one is a series of intranuclear flattened cisterns, parallel to each other and to the inner aspect of the nuclear envelope. The second one is a nuclear envelope protrusion into the cytoplasm occupied by a double membrane‐limited vesicle. Pores are found on the membrane of the vesicle facing the interior of the nucleus. In spermatocytes the nuclear pores are concentrated over certain areas and completely absent from others. In the regions where they are absent a single cytoplasmic cistern of rough endoplasmic reticulum is closely apposed to the outer membrane of the nuclear envelope. Early modifications of the nuclear surface appear in spermatids before the attachment of the acrosomic vesicle and may indicate an active role of the nuclear envelope in the morphogenesis of the acrosome. In round spermatids nuclear pores are absent from the area which is first related to the Golgi and later covered by the acrosomal cap. Single or multiple layers of cytoplasmic annulate lamellae are closely associated with the nuclear envelope over the pore rich areas. Frequently there are intranuclear accumulations of dense material adjacent to the annulate lamellae‐nuclear pore complex. The chromatoid body is usually present on the cytoplasmic side of this complex. In the elongating spermatids most annulate lamellae are free in the cytoplasm, often in relation with Golgi and chromatoid body remnants near the axial filament. Few stacks of annulate la‐mellae are noted adjacent to the pore rich nuclear regions. It is suggested that the described modifications are related to an active nuclear‐cytoplasmic inte

ISSN:0003-276X    

DOI:10.1002/ar.1091920404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY

摘要:

AbstractExisting evidence suggests that the aging human male experiences a gradual decline in testosterone production, a phenomenon that should be reflected in the Leydig cell population of the testis. It has been pro‐posed that Leydig cells diminish in number with increasing age, but conflicting claims characterize reports on this topic. We have reinvestigated this possibility by histometric analysis of perfused testes from 25 men ranging from 18 to 87 years of age. Average single Leydig cell volume (2,943 ± 623 μm3,XS. D.) did not change significantly with increasing age (r = 0.24, P>0.2), suggesting that surviving cells remain active. Total testis weight (43.5 ± 13.9 g) also did not change with age (r = 0.04, P>0.5). However, both total Leydig cell volume and the absolute number of Leydig cells per individual decreased significantly as functions of age (r = −0.71, P<0.002, and r = −0.61, P<0.005, respectively). Analysis of the relationship between these two parameters indicates that the total volume of Leydig cell cytoplasm contained within the human testis is determined by the number of cells present. Our results show that a pair of young adult testes endowed with more than 700 million Leydig cells at 20 years of age may be expected to undergo an attrition rate of approximately 80 million cells per subsequent decade of life. Thus, Leydig cell attrition is an important correlate of declining androgen status in a

ISSN:0003-276X    

DOI:10.1002/ar.1091920405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY

摘要:

AbstractThe spermatogonial populations in ten normal adult mice were analyzed using whole mounted seminiferous tubules. The undifferentiated A spermatogonia as well as the six generations of differentiating spermatogonia were clearly identifiable on whole mounts. Description plus quantitation of these cell types revealed that they behaved in essentially the same manner as their counterparts in the rat. Single undifferentiated A cells were classified as type A stem cell spermatogonia. They were distributed throughout the seminiferous epithelium, and by periodic mitoses, maintained their stock and furnished cells which would eventually differentiate. Although initially resembling the Asspermatogonia, the progeny which were destined to differentiate were classified as type Aalvspermatogonia because they were linked by cytoplas‐mic bridges, and because they usually underwent one or more synchronous mitotic divisions to form short chains of aligned cells. Ultimately, division of Aalcells were no longer seen, and the cells appeared to gradually acquire the typical morphological characteristics of A1spermatogonia; these continued to differentiate according to the well‐established pattern. It was concluded that the cyclic production of cohorts of A1cells in this manner would ensure a continual supply of spermatogonia for differentiat

ISSN:0003-276X    

DOI:10.1002/ar.1091920406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY

摘要:

AbstractIn adult male mice exposed to 300 R X‐irradiation, the sper‐matogonial population was selectively killed except for the radioresistant type Asstem cells. Type A spermatogonia were minimal two days after irradiation, when only 20% of the control population was present in stages 5‐6; these were predominately single and paired undifferentiated cells. When multiple injections of3HTdR were given between 2 and 3.5 days post‐irradiation, 90–95% of these survivors in stages 4‐6 became labeled. Enhanced proliferation of these stem cells, and at times when they were normally quiescent, led to restoration of all classes of spermatogonia by 11 days after irradiation.Several autoradiographic studies were undertaken to better characterize the radioresistant cells. In mice given single or multiple injections of3HTdR prior to irradiation, there was appreciable retention of label by those type Assper‐matogonia that had originally incorporated3HTdR in stages 2‐4. This labeling pattern was identical to that of the long‐cycling Asstem cells in nonirradiated testes. Since the long‐cycling Asstem cells are thought to be characterized by a prolonged G1or “A‐phase” which is known to be a highly radioresistant portion of the cell cycle, it was clear why these cells could preferentially survive irradiation doses that killed other spermatogonial types. It was proposed that following germ cell depletion, as after irradiation injury, the long‐cycling Assurvivors could be prematurely triggered from A‐phase into DNA synthesis, thereby, initiating restoratio

ISSN:0003-276X    

DOI:10.1002/ar.1091920407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY

摘要:

AbstractThe effects of 5α‐androstane‐3α,17β‐diol (3α‐diol) and 5α‐androstane‐3β, 17β‐diol (3β‐diol) were studied in rats hypophysectomized and treated daily for 30 days with the steroids, starting on the day of surgery (hypophysectomized, H) or 30 days following the removal of pituitary (hypophy‐sectomized regressed, HR). The ability of 3β‐diol to maintain and restimulate the prostate glands and seminal vesicles of castrated (C) and castrated regressed (CR) rats, respectively, was also studied. This androgen (3βdiol) was able to maintain as well as rejuvenate to some degree the sexual accessory glands of all treatment groups. The prostate glands and seminal vesicles in both castrated experimental groups showed increased stimulation with progressively higher dosages of 3β‐diol. At all dose levels, stimulation of seminal vesicles of CR rats was comparable to that of non‐regressed castrates. The prostate glands, on the other hand, showed better maintenance in the higher dosage group. In H rats, the stimulation of sexual accessory glands by both androgens was not significantly different than normal controls. The seminal vesicles and prostate glands of HR rats treated with 3α‐diol were well stimulated and comparable to those of H rats treated with 3α‐diol. The seminal vesicles of HR rats treated with 3β‐diol were also well stimulated, though not to the extent as those with 3α‐diol treatment. The prostate glands of the 3β‐diol treated HR rats were significantly smaller than those of the 3α‐diol treatment group. However, these miniature glands were morphologically stimulated as evidenced by mitosis of parenchymal cells and accumulation of secretory products in the alveoli. This study clearly indicates that 3β‐diol is biologically active and the degree of stimulation varies with the

ISSN:0003-276X    

DOI:10.1002/ar.1091920408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY

摘要:

AbstractThe histology and fine structure of the testis, epididymis and sex accessory glands were studied in young adult male rats administered testosterone enanthate, 120 μg/100 g body weight, three times weekly for 4, 8, or 12 weeks. The weights of the testis and epididymis decreased, and animals treated for 11 weeks were infertile. Alterations were found in the seminiferous tubules of all rats treated for 8 or 12 weeks, including the presence of many degenerating germ cells and a‐large decrease or absence of late spermatids. Study of different stages of the cycle of the seminiferous epithelium showed that the greatest number of degenerating germ cells, step 7 spermatids and pachytene primary spermatocytes, occurred at stages VII‐VIII of the cycle. Some normal appearing spermatogonia, primary spermatocytes and early spermatids remained in most seminiferous tubules. Sertoli cells contained many lipid droplets and lysosome‐like bodies, and degenerating cells were surrounded by Ser‐toli cell cytoplasm. The Leydig cells of treated animals were greatly reduced in size. Sperm progressively disappeared from the lumen of the middle segment and proximal part of the terminal segment of the epididymis after treatment for 8 or 12 weeks. Changes in the middle segment also included the appearance of intraepithelial cavities containing debris, and the presence within the epithelium of phagocytic cells that resembled leukocytes. The lumen of the proximal part of the terminal segment was often collapsed, while in the distal part of the terminal segment, the lumen was filled with cellular debris and degenerating sperm. Organelles of the principal cells of the epididymal epithelium appeared to be qualitatively unaltered. The weight of the sex accessory glands remained close to normal, and the presence of normal ultrastructural features suggested that production of secretions c

ISSN:0003-276X    

DOI:10.1002/ar.1091920409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY

ISSN:0003-276X    

DOI:10.1002/ar.1091920401

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY