Ectodermal Cell Layer Research Articles

Electron probe analysis of the calcium distribution in cells of the embryonic chick chorioallantoic membrane. II. Demonstration of intracellular location during active transcellular transport.

Electron probe analysis of the embryonic chick chorioallantoic membrane reveals that calcium is located at discrete sites in the ectodermal cell layer of the membrane. The calcium loci are found at characteristic sites within distinctive "capillary-covering" cells. Evidence is presented that the calcium identified by electron probe analysis is that pool of calcium undergoing active transcellular transport. Mitochondria and/or endoplasmic reticulum do not appear to be responsible for the observed calcium sequestration. It is suggested that the calcium might be contained within endocytotic vesicles, and a hypothesis is advanced which could reconcile endocytotic transcellular transport by specialized cells with previously proposed models for intracellular calcium ion regulation.

FINE STRUCTURES OF THE CARBON MONOXIDE SECRETING TISSUE IN THE FLOAT OF PORTUGUESE MAN-OF-WAR PHYSALIA PHYSALIS L.)

1. The carbon monoxide gas-secreting tissue (pneumadena) of Physalia is a single layer of ectodermal cells that are cuboidal to columnar in morphology. There is only one specific type cell and it is characterized by having the distal part, adjacent to the gas-interface surface, packed with large mitochondria. The mitochondria are unique in having few and small cristae. Most of the internum of the mitochondrion is occupied by a granular matrix. Compared with other secreting cells, there is very little smooth endoplasmic reticulum and less rough endoplasmic reticulum. There are numerous Golgi complexes and complex multivesiculate bodies. The nucleus is often enveloped by a cisternal space.2. The secretory epithelium is sensitive to adverse factors such as lowered temperature and presents changes that, though degenerate in appearance, may still have some functional ability to produce carbon monoxide. There is no evidence to indicate conclusively that gas is secreted by formation of vesicles in the cytoplasm....

Fine structure and function of planarian goblet cells

Planarians secrete quantities of mucus that appears to contain one or more glycoproteins as its major constituent. The fine structure associated with the various maturational and functional stages of a type of secretory cell of the planarian Dugesia dorotocephala is described which appears to be isomorphic with the goblet cells involved in the mucous secretion of mammals. This type of secretory cell, which occurs in large numbers in D. dorotocephala , differs from other cells which have been implicated in planarian mucous secretion. It originates and matures in the mesenchymal regions of the planarian, then migrates through the ectodermal basement membrane into the ducts penetrating the ectodermal cell layer. In its early stages it has a pronounced laminar endoplasmic reticulum and extensive Golgi complex activity. Electron transparent vesicles bud off from the tubes of the Golgi complex. These vesicles then, by swelling or coalescing, form the large mucus-filled Golgi vacuoles which almost completely fill the cytoplasm of the mature cell.

An ovarian tumor of dual nature in a rhesus monkey.

In the course of evaluating the toxicity of various anti-neoplastic agents, a female rhesus monkey was given a total of 236.50 mg of imidazolidinone in two intravenous injections 21 days apart. At the end of an observation period of 227 days after the second dose, necropsy revealed an enlarged spleen and replacement of the right ovary by a 168-gram cystic tumor. Two major and several smaller cysts were present. One of the large cavities was a typical dermoid cyst and the other was considered to be a papillary serous cystadenoma. The wall of the dermoid cyst contained several mature tissues derived predominately from the ectodermal and mesodermal cell layers.

The development of the stria vascularis in the mouse.

We used the electron microscope to study the evolution of the stria vascularis from a single layer of cuboidal ectodermal cells resting on spiral ligament fibroblasts to a composite epithelium of several layers of three different kinds of cells. In the process, complicated interdigitations form between neighboring cells which greatly increase surface area and would seem to increase fluid transport capacity. The number of microvilli decreases and each marginal cell's kinocilium disappears during the second week after birth. However, there is an increase in the number of clear, fluid-containing vesicles in the superficial part of the marginal cells.