Question

Spicules develop in sponges from cells located inside

• A. Pinacoderm
• B. Gastroderm
• C. Mesophyl layer
• D. All the above

Answer 1

Answer: (C)

Mesophyl layer

A. Pinacoderm is the outer layer of body wall of sponges consisting of flattened pinacocytes.

B. Gastroderm or gastral epidermis is the inner layer of body wall of sponges consisting of specialised flagellated cells called choanocytes or collar cells.

C. Mesophyl layer, also known as mesenchyme, is the inter connecting proteinaceous gelatinous matrix. Amoebocytes of various types are found moving in between thin layer such as archaeocytes, myocytes, chromocytes, thesocytes, scleroblasts, gland cells, trophocytes and collencytes.

Spicules in sponges are produced by Scleroblasts. Since Scleroblasts are present in mesophyl layer, therefore, spicules develop in sponges from cells located inside the mesophyl layer.

So, the correct answer is 'Mesophyl layer'.