The neural plate invaginates
beneath the epidermal layer to form the neural tube.
(1) It is a benign tumoral entity covered with columnar or cuboid epithelium with a cystic appearance characterized by proliferation of Von Brunn islets (transitional epithelium which invaginates
into lamina propria, a process induced by irritation in chronic cystitis mimicking carcinomatous invasion).
The uterus develops from celomic epithelium during the 6th week of development during which it invaginates
to form paramesonephric duct (mullerian duct).1-3
(1) The processus vaginalis peritonei (called canal of Nuck in the female) is a tubular fold of peritoneum that invaginates
into the inguinal canal anterior to the gubernaculum and descending testis, forming the tunica vaginalis testis in male.
Two tissue layers (endoderm and ectoderm) develop as one side of the embryo invaginates
to form the gut.
Testis descents and invaginates
the processus vaginalis from behind.
Telophase II--nuclei form, membrane invaginates
and cytokinesis occurs.
The mantle epithelium invaginates
and forms the so-called pearl sac, around which the pearl grows.
Intussusception is the condition whereby a segment of proximal intestine is telescoping or invaginates
into the lumen of the more distal bowel.
Intussusception occurs when one segment of bowel (intussusceptum) invaginates
into another (intussuscipiens) just distal to it leading to obstruction.1-3 Intussusception is the commonest cause of intestinal obstruction in children.1,3 Intussusception affects 1.5-4 cases per 1000 live births, with a male to female ratio of 3:2.1 The peak incidence is between 5 and 10 months of age.2
In sulcus vocalis, either the superficial layer of the lamina propria is absent altogether (usually causing severe dysphonia and requiring considerable vocal effort), or a portion of the epithelium invaginates
through the superficial layer of the lamina propria and adheres to the vocal ligament.
It is lined by a columnar ciliated epithelium that invaginates
to form crypts where long curved tubular glands originate.