Layers of the gastrointestinal tract The wall structure of the tubular (hollow) organs follows a general organization that is uniform along the gastrointestinal tract. The lumen of the organs is covered with tunica mucosa (mucous membrane) that is composed of…
You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log in here
Heart The primary component of the heart is the myocardium composed of cardiac muscle that has been described previously with the basic tissues. Briefly, cardiac muscle cells are elongated branched cells with centrally located, round or oval nuclei, many cells…
Lymphatic follicles Lymphatic follicles (lymphatic nodules) are spherical or ovoid structures composed of aggregated lymphocytes and a meshwork of reticular cells. Lymphatic follicles lack capsule, and they typically populate the lamina propria of the mucous membranes in the alimentary (gut-associated…
Epithelium Functionally, epithelium can be subdivided into two main types: covering (surface) epithelium and glandular epithelium. Surface epithelium covers mucous and serous membranes of tubular (hollow) organs as well as the outer surface of the body as epidermis. Structurally, surface…
FERTILIZATION Sperm capacitation ( 23-1 ) Fertilizing sperm must complete maturation and capacitation before sperm-egg fusion can take place. Sperm released from the testis and entering the epididymal duct display circular motion . After a 2-week maturation process during epididymal…
Development of the female reproductive tract The reproductive tract develops through the differentiation of wolffian ducts (male reproductive tract anlage) and müllerian ducts (female reproductive tract anlage). The female reproductive system consists of the ovaries , the ducts (oviduct, uterus…
DEVELOPMENT OF THE GONADS ( Primer 21-A ) An important aspect of gonadogenesis is the migration of cell precursors of the male and female gametes from the primary ectoderm into the wall of the yolk sac to become extra-embryonic .…
THE TESTES ( 20-1 and 20-2 ) The testes are paired organs located in the scrotum, outside the abdominal cavity. This location enables maintenance of the testes at a temperature 2 o C to 3 o C below body temperature.…
THYROID GLAND Development of the thyroid gland The thyroid gland (Greek thyreos , shield; eidos , form) develops as a median endodermal downgrowth at the base of the tongue. A transient structure, the thyroglossal duct , connects the developing gland…