Promonocytes differentiate from bone marrow stem cells (mono-blasts) and multiply to give rise to monocytes.

Monocytes spend only a short period of time in the marrow before being released into the bloodstream.

Monocytes are transported in the blood but are also found in connective tissues, body cavities and organs.

Outside the blood vessel wall, they are transformed into macropha-ges of the mononuclear phagocyte system.

Thrombopoiesis, or the formation of platelets, occurs in the red bone marrow.

Megakaryoblast is a large basophilic cell that contains a U-shaped or ovoid nucleus with prominent nucleoli. It is the last cell that undergoes mitosis.

Megakaryocytes are the largest of bone marrow cells, with diameters of 50 mm or greater. They undergo 4-5 nuclear divi sions without concomitant cytoplasmic division. As a result, the megakaryocyte is a cell with polylobulated, polyploid nucleus and abundant granules in its cytoplasm. As megakaryocyte maturation proceeds, «curtains» of platelet demarcation vesicles form in the cytoplasm. These vesicles coalesce, become tubular, and eventually form platelet demarcation membranes. These membranes fuse to give rise to the membranes of the platelets.

A single megakaryocyte can shed (i. e., produce) up to 3,500 platelets.

New words

reticular – сетчатый

sinusoids – синусоиды

granulocytes – гранулоциты

agranulocytes – агранулоциты

active – активный

yellow – желтый

glycoprotein – гликопротеин

erythropoietin – эритропоэтин

large – большой

amount – количество

hemoglobin – гемоглобин

degenerating – вырождение

capable – способный

division – разделение

spherical – сферический

indented – зазубренный

condensed – сжатый

chromatin – хроматин

Запомните следующие застывшие словосочетания.

to play _ chess to play the piano to play _ football to play the guitar out of _ doors

Запомните, что перед обращением артикль опускается.

Е. g. What are you doing, _ girls?

Заполните пропуски, где необходимо.

1. Do you play… piano?

2. There is… big black piano in our living-room.

3. It is at… wall to… left of… door opposite… sideboard.

4. My mother likes to play. piano.

5. She often plays… piano in… evening.

6..boys like to play… football.

7. What do you do in… evening? – I often play… chess with my grandfather.

8. Where are… children? – Oh, they are out of… doors… weather is fine today.

9. They are playing… badminton in… yard.

10. What… games does your sister like to play?

11. She likes to play… tennis.

12. Do you like to play… guitar?

13. What… colour is your guitar?

14. When we want to write… letter, we take… piece of… paper and… pen.

15. We first write our… ad dress and… date in… right-hand corner.

16. Then on… left-hand side we write… greeting.

17. We must not forget to leave… margin on… left-hand side of… page.

18. On… envelope we write… name and address of… person who will receive it.

19. We stick… stamp on… top of right-hand corner.

20. We posted… letter.

Answer the questions.

1. What is hematopoietic tissue composed of?

2. Where is myeloid found?

3. How is red marrow characterized?