ABSTRACT
The development of the argentaffin cell of the human gastro-intestinal tract is studied in 31 embryos and foetuses at closely graded stages of development. These cells are first seen in the epithelium of the duodenum at 47mm stage, but they do not assume their typical morphology. There are only a few argyrophile granule present around their nucleus. At the 89.3 mm stage the argentaffin cells appear in various parts of gastrointestinal tract and assume the typical morphology of infranuclear distribution of granules.The argentaffin cells assume various forms in sections: round, squamous, columnar, spindle, pyramidal, hammer-like, and flask-shaped. In gastric mucosa they are small, squamous or pyramical cells. They lie on the basal lamina with their apical ends not reaching to the stomach cavity. In intestine they are large columnar, spindle, pyramidal or flask-shaped cells. Their apical ends reach the luman. Sometimes their basal pole may penetrate to the lamina propria. In addition to these cells, in intestine there are also round argentaffin cells lacking luminal contact, with its argentaffin granules scattered here and there all over the cytoplasm. These difference in cell shape, granules distribution and luminal endings are likely related to the functional specialization, of argentaffin cell in different areas.Although most of the argentaffin cells are scattered singly in mucous epithelium, sometimes they may be present by twos and threes, and in appendix, they are often arranged in line. No argentaffin cell can be seen in any other part of the gut. They are differentiated in situ from epithelium. Therefore, we favor the idea that argentaffin cells are endodermal in origin.At the early embryo stage, the argentaffin cells are more numerous in villi, less numerous in intestinal crypt. As the embryo develops, they gradually increase in number both in villi and crypt (glands), but are more numerous in glands. In new born foetus the argentaffin cells are mainly scattered in glands.The argentaffin cells are very numerous in duodenum and particularly in appendix, less in stomach except pylorus. They are not found in esophagus.At various stages of development of the embryo the argentaffin cells are quite different in number. At the beginning, they are scarce. Following the development of embryos, their numbers increase rapidly and reach their maximum number at 21 weeks, 22 weeks and 23 weeks of age respectively. Thereafter the argentaffin cells decrease in number gradually, but they are still present at new born foetus.
ABSTRACT
Hair from 16 scalps of different ages (from 5 months to 77 years old) have been observed with SEM. The surface ultrastructure of the cuticle of the hair shaft is distinctly seen. The cuticles are arranged like shingles. Their free margins direct toward the end of the hair. The appearance and diameter of the shaft vary from age to age. The hair shaft of fetus is very fine. The cuticles are so broad that a single cuticle may encircle the shaft. They are parallel to each other. The intervals between successive free margins of cuticles are wide. Their free margin is smooth. The hair shaft of a 5-year old child is coarse. The cuticles vary in size. It requires a number of cuticles to encircle the shaft. The free margin becomes jagged and curved with microprotrusions on it. The intervals between free margins of the cuticles vary in width. The hair shaft of the youths is coarser. The cuticles are broad and arranged regularly. The intervals between free margins of the cuticles are comparatively narrow. There are numerous well developed microprotrusions on the free margin. The hair shaft of the middle aged is the coarsest and the intervals between free margins of the cuticles are the narrowest of all. There are less microprotrusions than those of the youths'. They are getting less and less, so that the free margin is partly smooth. Many cracks perpendicular to the free margin appear apparently and much debris fallen from the cuticle is attached to the surface of the the shaft. Sometimes falling of a whole cuticle may be observed. The hair shaft of the aged people is finer than that of the youths'. The intervals between cuticles with loose squamous arrangement are wider than those seen in the young and middle aged people. The free margin is usually smooth with only a few microprotrusions if any. Sometimes big and deep holes may be found on the surface of white hair. It is considered that the diameter of hair shaft, the size and arrangement of cuticles, the characteristic structures of free margin, the number of microprotrusions and with or without small debris attached to or holes appeared on the shaft are all related to age.
ABSTRACT
The neuroendoerine cells (NE cell) of the lung have been studied in 61 human fetuses by silver stain, immunocytochemical method and electron microscopic technique. The NE cells are mainly located in epithelium of conducting portion with various appearance. Some NE cells are neuron like with several processes. The 5-HT positive NE cells are often found in the epithelium of the primitive alveoli with pyramidal, squamous and tadpole-like appearance. Based upon their ultrastructure, the NE cells are rich in organelles and dense core vesicles (DCV). The NEB is often covered by a layer of cuboidal cells, but no nerve fibers are found among the cells in the NEB.The argyrophil cells usually appear in the 12th week, and reach the maximum number by 20th week. Before the 19th week, the argyrophil cells in the upper segment of the conducting portion are more numerous than those in the lower segment, while after 19th week the condition is just reverse. A regression curve made from the number of argyrophil cells and the thickness of intrapulmonary arteries in different fetal ages shows positive correlation.
