91. Resting mammary gland (HE)92. Lactating mammary gland (HE)
93. Umbilical cord (HE)94. Placenta (HE)
95. Chicken embryo (HE)
The mammary gland consists of 15 to 20 lobes,each of which is an individual conpound alveolar gland with its own lactiferous duct opening onto the surface of the nipple.The interlobar stroma is dense connective tissue and varying amount of fat.Within each lobe, similar interlobular connective tissue bands courses between lobules.
In an inactive gland, connective tissue is aboundant and and glandular elements are minimal.
Adipose tissue
lobule
Dense interlobular connective tissue
A lobule contains groups of small tubules lined with cuboidal or low columnar epithelium.These look like ducts and usually remain in this state as long as the gland is inactive.The tubules are embedded in loose cellular connective tissue, the intralobular connective tissue. Surrounding this is the dense interlobular connective tissue and fat.
lobule
Interlobular connective tissue
Intralobular connective tissue
Glandular tubules
The mammary gland is fully developed in lactation.The lobules are filled with alveoli.Their lumens contain milk secretion. The amounts of the connective tissue stroma and adipose tissue, relative to the parenchyma decrease considerably.
Interlobular connective tissuelobules
Milk is produced by the epithelial cells of the alveoli and accumulates in their lumens and inside the lactiferous ducts.The secretory cells become low cuboidal and their cytoplasm contains spherical lipid droplets of various sizes.
Interlobular connective tissue
Milk secretion
Lipid droplets
The umbilical cord connects the embryo/fetus to the placenta.It is covered by simple cuboidal epithelium of the amnion.It contains the umbilical vessels:2 umbilical arteries and 1 umbilical vein.These vessels are embedded in Wharton s jelly (mucous tissue).
One of the umbilical arteries
Amniotic epithelium
Wharton s jelly
The cells of the Wharton s jelly stain slightly basophilic.They have processes connecting with each other. The aboundant jellylike ground substance is rich in hyaluronic acid.The Wharton s jelly contains only a few fibers.
cells
It consists of a fetal part formed by the chorion, and a maternal part, formed by the decidua basalis.Fetal portion (chorion):It consists of the chorionic plate and the chorionic villi arising from it.The chorionic villi may be either free or anchored to the decidua basalis.The surfaces of the villi are bathed with maternal blood (intervillous sace) from the lacunae of the basal decidua.
Epithelium of the amnion
Chorionic plate
Chorionic villi
Base of villous stemm
The maternal portion comprises the basal plate or decidua basalis and its septal projections (placental septa) that form incomplete separations between individual cotyledons.
Decidua basalis
Intervillous space with maternal blood
Chorionic villi
Chorionic villi
Chorionic plate
Trophoblast of the chorion
Intervillous space
Chorionic villi
Branches of umbilical vessels with fetal blood
Intervillous space containing maternal blood
Extraembryonic connective tissue (mesenchyme)
Syncytial trophoblasts
Placental barrier
cytotrophoblast
Fetal blood
Intervillous space
ectoderm
endodermnotochord
Neural tube
somite
Intraembryonic coelom
Somatic mesoderm
Splanchnic mesoderm
Intermediate mesoderm /
nephrogonotom