Original Articles
Microanatomical study of chronological events in embryological development of human skin | |
Rubina Victor, Ankit Jain, Rashmi Jain, Amarjyoti Chaturvedi | |
Background: Literature describing chronological development of fetal skin beyond 12 weeks is scanty as there is scarcity of human fetuses for research in later stages of development due to diverse abortion laws and stringent guidelines on fetal research across the countries. Moreover, religious customs, ritual factors and sentimental issues also contribute to scarcity of fetal tissue for research. There is a great variability in the time of appearance of melanocytes and Keratinocytes, as shown by most studies. It is presumed to fall in a range from 12 to 20 weeks. Melanocytes appear in transitionally in dermis of fetal skin but there are inconsistencies in timings of appearance and disappearance. As the Medical Termination of Pregnancy Act (1971) allows abortion till 24 weeks of gestation, I have chosen this time as the upper limit of fetal age for the purposes of my study. This study will supplement existing literature on development of fetal skin beyond 12 weeks of development. Aims and Objectives: The current research aimed to assess the diagnostic utility of pap smear cytology and VIA as a screening test for various cervical lesions. Materials and methods: Determine fetal age by history and USG data. Arrange fetuses according to their gestational age by making their groups. Extract 5mmx5mmx5mm skin snips from dorsal aspect of forearm (for thin skin) and palm (for thick skin) with underlying subcutaneous tissue from fetal skin. Tissue fixation in 10% formalin followed by routine histological processing. All tissue blocks were alphanumerically coded. Tissue sections stained with H&E, Von Gieson. Observe, document and arrange findings in chronological order of embryological development. Results: In the initial weeks of development, only 2 to 3 layer of epidermis can be observed. In progressive weeks of development, skin appendages appear but not in well develop form. There is difference in the appearance of skin component in thin skin and thick skin. There is variability in the presence of rete pags. In some week of development, it is well defined while in higher weeks, it is not well defined in thin skin. Presence of fibroblast, melanocyte, keratin layer is less observed. Development of sweat gland begins in early stage and it is found in approximately all the sample. Presence of Rete pags shows the main difference in the thin & thick skin. Most of the data which have been collected after the observation, shows the appearance of skin appendages & component are well defined in group 4 which include fetus from 21 to 24 week of gestation. Conclusion: In the beginning weeks of development, epidermis is 2 to 3 layer thick in thin skin while it is 3 to 4 layer thick in thick skin. Keratinohyline present in all the group but keratin layer is not defined in any group. Rete pags create the main difference between thin & thick skin as it is observed in all the group of thick skin but in thin skin, it is not in regular basis. Carbohydrate observed in internal sheath of hair follicle. Most of the cells appears in thick skin of group 4 fetus like melanocytes, keratinocytes which can be easily observed in this group. Group 4 fetus sample shows presence of thin papillary dermis & thick reticular dermis in thick skin while it is not do defined in thin skin. Stratum spinosum begins to appears in group 4 in thin skin but it is not observed in other group. |
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