PS 2 - Schematic of Bull Testis Observe all layers of the wall of the scrotum and the association of the peritoneum with the testicle and scrotal wall. The numbers on this PS correspond to the numbers on PS 3. The following layers are present and further illustrated in PS 3 and PS 21. A. Skin and Dartos (no. 8) (scrotum) 1. Epidermis (stratified squamous epithelium) 2. Dermis (underlying connective tissue) 3. Dartos - the dartos is made up of smooth muscle, collagen and elastic fibers. It is a modified hypodermis or subcutaneous layer. It is most extensive at the bottom of the scrotum and thins as it covers the sides of the scrotum. It extends into the scrotal septum which divides the scrotum into two compartments, one for each testicle. B. Subcutis fascia (subdartic fascia)(no. 7) - this is a very small amount of loose connective tissue. C. Spermatic fascia (6A, 6B, 6C) trace fascia of scrotum back to body wall. 1. Internal spermatic fascia (ISF) a. Extension of transversalis fascia 2. Cremaster muscle (CM) a. Extension of internal abdominal oblique b. Where no muscle is present, it continues as a thin sheet of c.t. between ESF and ISF. 3. External spermatic fascia (ESF) a. External spermatic fascia (ESF) 4. Spermatic fascia - ESF + CM + ISF D. Tunica vaginalis parietalis (common tunic)(no. 5) 1. A layer of mesothelium and a thin layer of c.t. (peritoneum) - it blends with the c.t. below, which is the ISF. E. Vaginal cavity (no. 4) 1. A potential space between the t.vaginalis parietalis and t. vaginalis visceralis. 2. This cavity is continuous with the abdominal cavity in domestic animals, but there is no continuity in man. F. Tunica vaginalis visceralis (proper tunic)(no. 3) 1. A layer of mesothelium and a thin layer c.t. This derivative of the peritoneum blends with the c.t. enveloping the ductus deferens, spermatic vessels and nerves, epididymis, and the t. albuginea of the testicle. G. Tunica albuginea (No. 2) 1. A fibrous structure composed of dense c.t. Smooth muscle may be present in the horse. 2. Stratum vasculare - vessels are present at varying depths depending upon the species. 3. The T. ALBUGINEA is continuous with the MEDIASTINUM TESTIS and the SEPTULAE TESTIS. .