Rings of rat aorta cultured in Matrigel, a reconstituted gel composed of basement membrane molecules, gave rise to three-dimensional networks composed of solid cellular cords and occasional microvessels with slitlike lumina. Immunohistochemical and ultrastructural studies showed that the solid cords were composed of endothelial sprouts surrounded by nonendothelial mesenchymal cells. The angiogenic response of the aortic rings in Matrigel was compared to that obtained in interstitial collagen, fibrin, or plasma clot. Morphometric analysis demonstrated that the mean luminal area of the microvascular sprouts and channels was significantly smaller in Matrigel than in collagen, fibrin, or plasma clot. The percentage of patent microvessels in Matrigel was also markedly reduced. Autoradiographic studies of 3H-thymidine-labeled cultures showed reduced DNA synthesis by developing microvessels in Matrigel. The overall number of solid endothelial cords and microvessels was lower in Matrigel than in fibrin or plasma clot. A mixed cell population isolated from Matrigel cultures formed a monolayer in collagen or fibrin-coated dishes but rapidly reorganized into a polygonal network when plated on Matrigel. The observation that gels composed of basement membrane molecules modulate the canalization, proliferation, and organization into networks of vasoformative endothelial cells in three-dimensional cultures supports the hypothesis that the basement membrane is a potent regulator of microvascular growth and morphogenesis.

Size and density of microvessels in close proximity to normal, hyperplastic, and in situ neoplastic mammary epithelium were evaluated with a morphometric method. Human tissue samples were obtained from breast mammoplasty or biopsy specimens with diagnosis of either epitheliosis or ductal carcinoma in situ. The mean vessel size was significantly enhanced in hyperplastic and neoplastic lesions as compared to mammoplasty specimens considered as 'normal'. On the contrary, the density of the microvessels around the epithelium was comparable in the three groups of tissues. It appears that as long as the basement membrane remains intact, sprouting of new vessels around neoplastic lesions is not manifested.

An important issue of prognostic significance is to differentiate a cutaneous metastasis of a neuroendocrine carcinoma from the primary small cell-undifferentiated carcinoma of the skin (Merkel cell carcinoma).

A cutaneous metaplastic synovial cyst is a rare entity that is probably caused by trauma or surgery. We report the second case of cutaneous metaplastic synovial cyst in a child with Ehlers-Danlos syndrome. His father is also affected with Ehlers-Danlos syndrome, and his diagnosis is substantiated by the demonstration of reduced synthesis of collagen type V.

Appendicular diverticulosis is a rare condition observed in about 0.004–2% of all appendectomy specimens. Risk of perforation/bleeding is high and a relevant association with mucinous neoplasms is known. Appendectomy is indicated even in case of occasional finding. We present the case of a 22-year-old man who entered the Emergency Room for pain in right iliac fossa. Blood tests showed only a slight increase in C-reactive protein. Abdominal ultrasound (US) evidenced an appendix with thickened walls and a rounded fluid-filled hypoechoic lesion at its distal tip. Laparoscopic appendectomy confirmed the presence of mucocele. Postoperative course was uneventful and the patients discharged on postoperative day 3. Histological examination indicated diverticulitis/peridiverticulitis of the appendix and acute suppurative appendicitis. No perforation of the diverticula was detected. No neoplastic epithelium/mucous material was observed. In our case, preoperative US proved to be a useful alternative to computed tomography for the diagnosis.