HISTOGENESIS OF THE HUMAN RETINA / 解剖学报

62 cases of human fetal and 2 neonatal retina specimens were observed with LM. The thickness of the outer pigmented epithelium was reduced and changed from pseudostratified columnar to a simple cuboid layer at 8-9 weeks. The initial differentiation of neuro-epithelium was divided into an outer and an inner neuroblastie layers, between them was a transient layer of Chievitz which disappeared at 10-11 weeks. At the same time the differentiating ganglion cells were migrated from the inner neuroblast layer toward the marginal layer. The developing ganglion cell layer, inner plexiform layer and nerve fiber layer could be identified until 12-13 weeks. During 11-14 weeks, the precusors of cones were occurred at the outermost row of outer neuroblast layer, and the developing rods, outer plexiform layer and inner nuclear layer were recognizable during 15-20 weeks. Differentiation of the peripheral retina was later than the central portion during the fetal period. Histogenesis; Retina; Optic disc; Human fetus

HISTOGENESIS OF THE HUMAN STOMACH / 解剖学报

In this article we collected 2 embryos and 69 fetuses between 7 and 30 weeks of gestational age and 3 neonates to study the development of the human stomach by histological, histochemical and immunogold-siver methods. In 7-week embryo, the superficial layer of gastric mucosa was stratified columnar epithelium, containing a large amount of glycogen. In 9-week fetus, simple columnar epithelium, gastric pits and glandular buds were observed. At this stage a few parietal cells could be identified at the bottom of the glands. The pyloric glands contained parietal cells as fundic glands. At 13-14 week the muscularis mucosa appeared and the wall of stomach formed definitively as the adult. A few argyrophil cells in antrum and fundus were found at 12-week fetus. They scattered in the surface epithelium and concentrated in the lower portion of the glands. The argyrophil cells were round, pyramidal or spindle in shape. More argyrophil ceils were found in the antrum from 14-week on. At 18-week, the argyrophil cells were most numerous. Some cells possessed processes extending to the basement membrane or parietal cells. Between 15-30 weeks various shaped EC cells in fundus were found, with some open-type endocrine cells. G cells in antrum were mostly rounded and often in groups at 13,16 and 21 week. Developing G cells were observed under EM.

HISTOGENESIS OF THE HUMAN THYROID GLAND / 解剖学报

Thyroid glands from 80 human fetuses, 7～31 weeks in gestational age were obtained to study the morphological development of thyroid glands by histochemical, immunohistochemical and TEM techniques. During 7～8.5 weeks the glands composed mostly of epithelial cell cords and abundant glycogen were seen in the cytoplasm of the cells. Some follicles and small accumulations of colloid in the center of the follicles appeared at 12～12.5 weeks and less glycogen was found in the cells. C cells were distributed mainly in the posterior region of the upper pole of both lobes, they usaually occurred singly or in small groups. During intrauterine life, C cells occupied three positions. They are found between follicular cells, between follicular cell and basement membrane and between follicles. But they are situated predominantly in the follicular wall. Three morphological variants were found in the human fetal C cells: (1) spherical or oval cells, (2) polygonal or pyramidal cells (3) cells with a cytoplasmic process. Developing C cells seem to have few secretory granules by TEM and argyrophilic reaction in semithin sections.

HISTOGENESIS OF THE HUMAN APPENDIX / 解剖学报

In this article 108 human fetuses from 12 to 30 weeks of gestation, 3 neonates and a 1.5 years child were used for study of the histogenesis of the appendix.In 12 weeks old fetus, the appendix showed small lumen and thin wall. The mucosa presented intestinal villi and crypts. The endocrine and goblet cells could be found. The circular muscle and serous membrane had differentiated. In the specimens of 13 to 15 weeks, the lamina propria contained diffused lymphatic tissue and lymphatic follicles. On such sites, the intestinal villi were absent. The surface epithelium became attenuate and composed of cuboid or lower cuboid cells. The outer longitudinal muscle layer was evident. The scattered muscularis mucosa was found. At 16 weeks, the endocrine cells appeared and showed various forms. The open-type or closed-type endocrine cells could be distinguished easily. Under EM, based on the morphology of the basal granules, the endocrine cells might be divided into two types. The granules were cell enclosed in a limiting membrane. One type of the granules was round and various in size, and another type was irregular. In the surface epithelium covered on the lymphatic tissue, the microfold cells could be found. They showed irregular microvilli or mierofolds and numerous apical micropinocytotic vesicles. At 18.5 weeks, the villi tended to merge each other. At 20 weeks, the muscularis mucosa was formed and the 4 layers of appendix resembled those of the normal adult. We found endocrine cells aggregated into Segi's cap on the apex of the villi in 7 fetuses of 16-21 weeks. The T or B lymphocytes could be identified as early as 13.5 weeks by immunologic method. We found the percentage of the B lymphocytes decreased with the gestation age, and this fact suggested that the appendix might be a B lymphocyte pool during the fetal period.

HISTOGENESIS OF THE HUMAN LIVER / 解剖学报

Liver specimens from 41 human fetuses of about the 7 th week gestation tonewborn were studied.The liver tissues were fixed in proper fixatives and stainedwith H.E.,Unna's method for RNA,McManus PAS reaction for glycogen,Gomori'sCa-Co method for AlP and Altmann's method for mitochondria.In 7-week old embryo,the liver shows trabeculae of recognizable liver cells andsinusoids only.The ingrowth of connective tissue about the portal vein is observedduring the 8th week.The formation of lobular arrangment in adult liver startsfrom 9～12 weeks.The inter-and intra-lobular bile ducts derived from the peripor-tal limiting plate at the same period.The hepatic cells of the 8th week embryo arrange in plate form.The hepaticplate is plastic and changes in various thickness depending upon the size of theadjacent sinusoids.The cytoplasm of embryonic hepatic cell is rich in RNA,glycogen and mitochon-dria and is weak in AlP activity.However zonation does not appear in liverlobules during fetal life.

HISTOGENESIS OF THE HUMAN TESTES / 解剖学报

Testes of 35 human fetuses from 7-week gestation to newborn were studied. The testes were fixed in Carnoy's solution and stained with HE,Unna's method for RNA and McManus PAS reaction for glycogen. In 7-week old embryo(CRL 18mm),the gonad shows no morphological indication of sex,and still is indifferentiated.In the 13-week embryo,the basic structural of the testis such as thickened fibrous tunica albuginea,prominent sex cords and accumulative interstitial cells are clearly identifiable. The sex cords are now called testicular cords which were composed of primordial germ cells and supporting cells.The cords lumen appeared at 14.5-week of gestation and the germ cells in the cords are distinguished by the size of cell bodies,contain- ing a large amount of glycogen and large round nuclei with conspicuous nucleoli. The eosinophil accumulative interstitial cell(Leydig cell)may be divided into 3 types:inmature,mature and degenerating.In the 20-week embryo the number of the interstitial cells decreased sharply.

HISTOGENESIS OF THE HUMAN OVARY / 解剖学报

The ovaries of 26 human fetuses from 10 to 38 weeks of age were fixed in Carnoy's solution and stained with HE, PAS and Unna's method for RNA. Development of human ovaries at embryologic period was divided into 3 stages:1.Oogonia stage: From 10 to 15 weeks groups of dividing oogonia were observed. Their cytoplasma contained glycogen.2.Primary oocytes stage: At 15 to 20 weeks, the primary oocytes in various appearance of meiotic prophase were presented. The oocytes contained RNA granules. During this stage there was extensive degeneration of both oogonia and oocyte. 3.Primordial follicle stage: Between 15 and 17 weeks, the primordial follicles began to appear at cortico-medullary junction. After 20 weeks numerous primordial follicles filled the cortical region. A few primary and secondary follicles were developed from 26 weeks onward, as a result of stimulation of the fetal ovaries by maternal gonadotropins. The interstitial gland cells in the fetal ovaries were scattered cells at the corticomedullary junction from 12 weeks onward.