BIO380H5 Lecture Notes - Lecture 7: Prolactin, Chromatin, Osteocalcin
Document Summary
Cytodifferentiation: @ the level of individual cells in which the cells that make up a tissue undergo increasing specialization. Histogenesis: various cell types develop in concert to form specific tissues. The skin is adapted for local functional requirements (scalp/palms: these local variations result from inductive interactions between the ectoderm and underlying mesenchyme. 1st month ectoderm is a single layer of ectodermal cells. 2nd month periderm involved in exchange of water, sodium and glucose between amniotic fluid and epidermis. Melanoblasts: 2nd month from neural crest migrate into embryonic dermis then to epidermis: they start to produce pigment granules (melanosomes) at mid pregnancy, melanocytes of darker skinned people contain more melanosomes per cell, albinism = no pigment. Langerhans" cells: late in first trimester arise from precursors in the bone marrow (which originates from mesoderm); peripheral components of immune system, present antigens and cooperate with t-lymphocytes.
